OBJECTIVE To evaluate the efficacy and tolerance of irinotecan (CPT-11) in combination with bolus and continuous infusion of 5-fluorouracil (5-FU) and leucovorin (LV) (FOLFIRI regimen) as first-line treatment of elderly patients with metastatic colorectal cancer (MCC). METHODS Thirty consecutive, previously untreated patients with metastatic colorectal cancer, aged (median 76 years; range 70-84) were enrolled. The performance status (WHO) was 0 in 8, 1 in 16 and 2 in 6 patients; 19 (63%) patients had prior surgery and 8 (27%) adjuvant chemotherapy. CPT-11 (180 mg/m(2) as a 90 min i.v. infusion) was administered on day 1, LV (200 mg/m(2) as a 2-hour i.v. infusion), 5-FU (400 mg/m(2)/d i.v. bolus followed by 600 mg/m(2)/d as a 22-hour i.v. continuous infusion) were given on days 1 and 2 every 2 weeks. RESULTS Complete response was achieved in one (3.3%) patient and partial response in 10 (33.3%) (overall response rate: 36.6%; 95% C.I.: 26.6-48.4%); 11 (36.6%) patients had stable disease and, 8 (26.6%) disease progression. The median duration of response was 7.5 months and the median time to disease progression 7.0 months. After a median follow-up period of 17 months, the median overall survival was 14.5 months. Main toxicities were: grade 3-4 neutropenia (n = 6; 20%), grade 3 thrombocytopenia (n = 1; 3.3%), grade 2 anemia (n = 9; 30%), grade 3-4 diarrhea (n = 5; 17%) and grade 3 asthenia (n = 3; 10%). There was one treatment-related death due to neutropenic sepsis. CONCLUSIONS The FOLFIRI combination is an active regimen with manageable toxicity as front-line treatment in patients above 70 years of age.