Background: Based on retrospective experiences, gender seems to affect the safety profile of chemotherapy (CT), with a higher incidence of CT-related adverse events (AEs) among females than males. Here we focus on the impact of gender on the toxicity of FOLFOXIRI/bevacizumab (bev) as compared with doublets (FOLFOX or FOLFIRI)/bev in two randomized phase III studies by GONO: TRIBE and TRIBE2. Methods: The risk of experiencing CT-related AEs in males and females was estimated in univariable analysis in the overall safety population and according to treatment arms (doublets/bev and FOLFOXIRI/bev). In order to assess the independent weight of gender on the risk of developing AEs, multivariable logistic regression models were built. Results: Among 1187 patients enrolled in TRIBE and TRIBE2 studies, 1176 (684 males, 58%, and 492 females, 42%) were included in the safety population. Overall, women had a significantly higher risk of CT-related AEs, in particular gastrointestinal and hematologic AEs, asthenia and alopecia, independently of the treatment arm. The risk of CT-related AEs was increased with FOLFOXIRI/bev vs doublets/bev independently of gender (p for interaction: 0.329). Notably, among women treated with FOLFOXIRI/bev 50% and 68% experienced any grade of vomiting and nausea, respectively. Conclusions: Female mCRC patients have a higher risk to develop CT-related AEs. In women treated with FOLFOXIRI/bev the high incidence of nausea and vomiting may suggest the need for an intensification of the antiemetic prophylaxis.