Data from the Louisiana Agricultural Experiment Station Ben Hur Research Farm were used to compare the performance of EPIC-WT and DRAINMOD models in simulating the effect of subsurface drainage systems on surface and subsurface drained volumes and the fluctuations of field watertable depth. Both models overestimated the total cumulative drainage flows for the simulation period (1981-1987). The long-term cumulative values simulated by DRAINMOD and EPIC-WT were 7% and 32% greater than those observed for surface drainage volumes, and 34% and 20% greater than the observed volumes for subsurface drainage. The slope and correlation coefficients of the regression lines associated with EPIC-WT monthly flows were 0.86 and 0.85 for the surface volumes, and 0.98 and 0.92 for the subsurface volumes. The regression equation describing the linear relationships between the monthly observed flows and the flows predicted by DRAINMOD had slope and correlation coefficients of 0.95 and 0.90 for surface volumes, and 1.02 and 0.77 for subsurface volumes. The watertable fluctuations were predicted better by DRAINMOD than EPIC-WT during relatively dry periods when the watertable depth was below the root zone; however, the overall performances of the two models in simulating the watertable fluctuations over the seven-year period were about the same.