Patients with neuroendocrine carcinomas (NECs) grade 3 have a poor prognosis. Etoposide-platinum combination is the standard chemotherapy but the role of a second-line therapy remains unknown. Irinotecan alone or in combination has shown some efficacy in patients treated for small cell lung cancer which had pathological similarities with neuroendocine tumors. The aim of this study is to determine safety and efficacy of the FOLFIRI regimen in patients with NECs grade 3 after failure of etoposide-platinum combination. This study was retrospective, including patients with NECs grade 3 and treated with the FOLFIRI regimen after progression or toxicity of etoposide-platinum combination in first-line. Patients with Eastern Cooperative Oncology Group (ECOG) performance status ≥3 and/or serum alkaline phosphatase ≥5×upper limit of normal value (ULN) and/or bilirubin ≥1.5×ULN were excluded. Among 39 patients who failed etoposide-platinum combination, 19 (49%; 12 women, median age 53 (29-78) years) received the FOLFIRI regimen with a median number of 6 (1-16) courses. Six patients (31%) had at least one episode of grades 3-4 toxicity (neutropenia, n=3; diarrhea, n=3) without toxic death. Six patients (31%) had objective response, 6 (31%) stable disease, and 7 (38%) tumor progression. Median progression-free survival under FOLFIRI was 4 months. Overall survival was 18 vs 6.8 months in noneligible patients. FOLFIRI regimen is a safe and potentially efficient chemotherapy given as second-line in patients with NECs grade 3 who remain in good condition and with correct liver tests after failure of etoposide-platinum combination. These results should be confirmed in a future prospective study.