In this paper, we analyze empirically the interrelationships among leverage, debt maturity and investment and the effects of their interactions with growth opportunities on leverage,debt maturity and investment of firms listed on Korea Exchange. In terms of methodology, we develop the structural equations model that integrates leverage, debt maturity, and investment model. The main results of this study can be summarized as follows. In leverage model, debt maturity has a significant and positive effect on leverage. This result supports the liquidity risk hypothesis that predicts a positive relation between debt maturity and leverage(Diamond, 1991 and 1993; Sharpe, 1991). Growth opportunities have a significant and negative effect on leverage. This result provides strong support for the underinvestment hypothesis(Myers, 1977). Interaction variable between debt maturity and growth opportunities has a significant and negative effect on leverage, implying that for high growth firms, the overall positive relation between debt maturity and leverage may become weaker. With respect to the overall effect of debt maturity itself and the interaction between debt maturity and growth opportunities on leverage, debt maturity has a significant and positive effect on leverage. In debt maturity model, leverage has a significant and positive effect on debt maturity,which is consistent with the result in leverage model. It provides further evidence that high liquidity risk caused by high leverage policy can be moderated by long-term debt maturity and that long-term(short-term) debt maturity and high(low) leverage can be used as supplementary strategies to avoid the threat of suboptimal liquidation. Growth opportunities have a significant and negative effect on debt maturity. This suggests that there is economic relation between growth opportunities and debt maturity. Interaction variable between leverage and growth opportunities has a significant and positive effect on leverage, implying that for high growth firms, the overall positive relation between leverage and debt maturity may become stronger. With respect to the overall effect of leverage itself and the interaction between leverage and growth opportunities on debt maturity, leverage has a significant and positive effect on debt maturity. In investment model, leverage has a significant and negative effect on investment. This result is consistent with the prediction of agency theory that there is a negative relation between leverage and investment, and it supports the underinvestment hypothesis. Debt maturity has a significant and positive effect on investment. Growth opportunities have a significant and positive effect on investment, which is consistent with Tobin-q theory that high growth firms increase investment level. Interaction variable between debt maturity and growth opportunities has a significant and negative effect on investment, implying that for high growth firms, the overall positive relation between debt maturity and leverage may become weaker. With respect to the overall effect of debt maturity itself and the interaction between debt maturity and growth opportunities on investment, debt maturity has a significant and negative effect on investment. Considering both high and low growth firms in leverage model, debt maturity has a significant and positive effect on leverage. This supports the contention that there is a positive relationship between debt maturity and leverage. For high growth firms, growth opportunities have a significant and negative effect on leverage, while for low growth firms, growth opportunities have a significant and positive effect on leverage. That is, high growth firms follow the underinvestment hypothesis (Myers, 1977), while low growth firms follow the overinvestment hypothesis(Jensen, 1986;Stulz, 1990). For high growth firms, interaction variable between debt maturity and growth opportunities has a significant and negative effect on leverage, while for low growth firms, it has a significant and positive effect on leverage. Considering both high and low growth firms in debt maturity model, leverage has a significant and positive effect on debt maturity,supporting the contention that the extension of debt maturity and leverage expansion are able to use as supplementary strategies on liquidity risk. Additionally, growth opportunities for both high growth and low growth firms have a significant and negative effect on debt maturity. This suggests that firms prefer the reduction of debt maturity than the strategy of leverage reduction to relieve the underinvestment problems. For high growth firms, interaction variable between leverage and growth opportunities has a significant and negative effect on debt maturity, while for low growth firms, it has a significant and positive effect on debt maturity. Considering both high and low growth firms in investment model, lagged leverage has a significant and negative effect on investment. This result is consistent with the prediction of agency theory that there is a negative relation between leverage and investment, and it supports the underinvestment hypothesis. Lagged debt maturity with high growth and low growth firms have significant and negative effect on investment. Lagged growth opportunities with high and low growth firms have significant and positive effect on investment. It is consistent with Tobin-q theory that firm with high growth has more investment. For high growth firms,interaction variable between lagged leverage and lagged growth opportunities has a significant and positive effect on investment, while for low growth firms, it has a significant and negative effect on investment. In conclusion, it is necessary to examine the potential interactions among leverage, debt maturity and investment to investigate the dynamics of financing decisions on investment. Our results provide a number of fresh insights into the overall effects of leverage and debt maturity and the interactions among leverage, debt maturity and growth opportunities on leverage, debt maturity and investment. This paper may have a few limitations because it may be an only early study about the interrelationships among leverage, debt maturity and investment of Korean firms. Therefore,we think that it is necessary to expand sample firms and control variables, and use more elaborate analysis methods in the future studies.