The aim of this study was to assess the safety and efficacy of biweekly irinotecan plus leucovorin-modulated 5-fluorouracil i.v. bolus in metastatic colorectal carcinoma according to the age of patients. For this purpose, we have analysed 108 patients randomly allocated to receive irinotecan 200 mg m(-2) i.v. (1-h infusion) on day 1, and L-leucovorin 250 mg m(-2) i.v. (1-h infusion) plus 5-fluorouracil 850 mg m(-2) i.v. bolus on day 2 every 2 weeks (IRIFAFU) in our previous SICOG 9801 trial. According to age, patients were retrospectively divided into three groups: younger (</=54 years, n=37), middle-aged (55-69 years, n=64), and elderly (>/=70 years, n=17). Apart from gender, pretreatment characteristics were well balanced across the three groups. WHO grade >/=3 neutropenia and diarrhoea affected on the whole 46 and 16 patients, respectively, without any significant difference according to age-grouping. Patients aged </=54 years stayed on therapy for a longer time (median 24 vs 14-15 weeks), and received more cycles (median 9 vs 7), than the older ones. Only one patient in the young group withdrew consent to therapy as opposed to four patients each in the aged and elderly one. Response rate was 38% for younger patients, 34% for aged, and 35% for the elderly ones. Median time to progression was 7.4, 8.0, and 5.3 months, and median survival time was 13.4, 15.3, and 13.9 months, respectively. We conclude that IRIFAFU given every other week may represent a suitable therapeutic option also for elderly patients with metastatic colorectal carcinoma.