The aim of this study was to retrospectively evaluate the effect of adding CPT-11 to postoperative chemotherapy for stage III colorectal cancer. The subjects were 94 patients, including 60 in stage IIIa (<or=3 positive nodes) and 34 in stage IIIb (>or=4 positive nodes), who underwent curative resection. The clinical outcome was compared between patients receiving 5-FU/LV plus CPT-11 (FLC group) and patients receiving 5-FU/LV alone (FL group). The FLC group (54 patients) had a 3-year relapse-free survival (3Y-RFS) of 68.7%, a 5Y-RFS of 68.7% and a 5Y-OS of 67.1%, while the FL group (40 patients) had a 3Y-RFS of 67.5% (n.s.), a 5Y-RFS of 64.9% (n.s.), and a 5Y-OS of 77.3% (n.s.). There were no significant differences of these parameters between the two groups. For stage IIIa patients, the corresponding survival rates were 92.4, 92.4 and 90.9% in the FLC group (29 patients) vs. 64.5% (p=0.024), 61.1% (p=0.018), and 77.1% (n.s.) in the FL group (31 patients). For stage IIIb patients, the rates were 36.6, 36.6 and 24.8% in the FLC group (25 patients) vs. 77.8% (n.s.), 77.8% (n.s.), and 77.8% (n.s.) in the FL group (9 patients). These results suggest that the 3Y-RFS and 5Y-RFS of patients with stage IIIa colorectal cancer were significantly improved by adjuvant chemotherapy with 5-FU/LV plus CPT-11.