In metastatic colorectal cancer, an intensive first-line regimen may impair second-line treatments. We evaluated the outcome of second-line therapies among the 196 patients treated with 5-fluorouracil, leucovorin, oxaliplatin, irinotecan (FOLFOXIRI) in three trials. Activity and efficacy were in line with previous studies and retreatment with triplet achieved promising results. FOLFOXIRI does not impair second-line treatments and in selected patients rechallenge may represent a valid option. Purpose: FOLFOXIRI demonstrated higher efficacy compared to 5-fluorouracil, leucovorin, irinotecan (FOLFIRI) as first-line treatment of metastatic colorectal cancer. We evaluated the outcome of second-line treatments among 196 patients treated with first-line FOLFOXIRI in three consecutive trials conducted by the Gruppo Oncologico Nord Ovest group. Patients and Methods: One hundred seventy-two of 196 patients so far progressed and 136 (79%) received second-line therapies: 32 (24%) were rechallenged with FOLFOXIRI, 52 (38%) were treated with irinotecan- or oxaliplatin-based doublets, and 52 (38%) received fluoropyrimidine plus mytomicin C or single-agent chemotherapy. Only 10 patients received bevacizumab (3) or cetuximab (7) with chemotherapy. Activity and efficacy data were collected and subgroup analyses were performed according to the regimen administered. Results: Overall response rate (RR) was 23%; median progression-free survival (PFS) and overall survival (OS) were 5.9 and 13.2 months, respectively. At an exploratory subgroup analysis, retreatment with FOLFOXIRI was associated with longer PFS (8.2 versus 6.3 months; P = .003, hazard ratio [HR] = 0.61) and OS (19.3 versus 14.0 months; P = .02, HR = 0.57) compared with doublets; single-agent chemotherapy or fluoropyrimidine plus mytomicin C was significantly lower in terms of RR (8%), PFS (3.0 months), and OS (8.7 months) compared with FOLFOXIRI or doublets. Conclusions: First-line FOLFOXIRI does not impair the efficacy of second-line treatments. In some patients rechallenge with FOLFOXIRI may represent a valid option, although potential imbalances in prognostic factors due to better patient selection should be considered.