In Veterans General Hospital-Taipei, 25 patients with metastatic or recurrent colorectal adenocarcinoma were treated with a 5-day course of 5-FU (370 mg/M2/d) and high dose leucovorin (200mg/M2/d), repeated every 28 days until a progression of disease was evident. Twenty-one patients had evaluate tumor response. Among the 16 patients with measurable disease, three patients achieved partial response (PR), and their response durations were 2 months, 6 months and 6+ months. Five patients had stable disease (SD) for 4,4,6,7, and 10 months before its progression. Among the 5 patients with documented abdominal carcinomatosis, four remained stable without any progression for 5,6,12 and 12 months after treatment. The overall response rate was 57% (3PRS, 9SDs). Seven of the 12 responders had prior 5-FU exposure. Nine patients had progressive disease and 7 of them died within a few months after the start of treatment. The median duration of response was 6.7 months. The median survival for responders was 9.8 months, and for non-responders, 3.7 months. Performance status (PS) was a main determinant of response. Among the patients with PS = 0 (6 patients), there were 2 PRs and 4 SDs and with PS = 1 (8 patients), 1PR and 4 SDs. When PS = 2 or 3 (7 patients), only 2 SDs were noted. All the 25 patients were put into toxicity test to find in a mild to moderate, easily controlled state. There were 3 (12%) patients with grade 2-3 mucositis, 6 (24%) with grade 2 diarrhea, 13 (50%) with nausea and vomiting. Only 3 cases developed leucopenia but without thrombocytopenia.(ABSTRACT TRUNCATED AT 250 WORDS)