This study used financial analysts' earnings forecast data from the FN-Guide database for the three-year period from 2001 to 2003 to examine whether herding behavior in financial analysts' earnings forecasts exists in the Korean securities market and to identify the determinants of earnings forecast herding. The analysis results are as follows. First, the existence of herding in financial analysts' earnings forecasts in the Korean securities market was confirmed. Second, analysts' individual characteristic factors were found to have no significant association with herding probability. Third, regarding variables related to analysts' environmental factors, it was found that analysts affiliated with smaller securities firms, or those covering smaller firms and firms with higher institutional investor ownership, had higher herding probabilities. This implies that analysts' environmental factors are significant determinants influencing herding probability.