Background: FOLFOXIRI/bevacizumab is a valuable upfront option in mCRC based on results of phase III TRIBE and TRIBE2 studies: 1187 pts aged 18–70 years with ECOG performance status (PS) ≤ 2 or between 71–75 years with an ECOG PS of 0 were randomized to receive first-line FOLFOXIRI/bevacizumab or a doublet (FOLFIRI in TRIBE and mFOLFOX6 in TRIBE2)/bevacizumab. Here, we aimed at assessing the effect of the intensification of the upfront chemotherapy (triplet versus doublet) in terms of safety and efficacy in pts aged < 70 versus 70-75. Methods: Subgroup analyses for ORR, PFS, G3/4 overall adverse events (AEs), chemo-related and bevacizumab-related AEs were performed according to baseline age. Results: 182 (15%) out of 1187 pts were 70-75 years old (97 in the FOLFOXIRI/bevacizumab and 85 in the doublets/bevacizumab arms). The benefit provided by the intensification of the upfront chemotherapy was independent of the age subgroup in terms of both ORR (p for interaction = 0.684) and PFS (p for interaction = 0.634). The risk of overall and chemo-related G3/4 AEs was increased with the triplet independently of age (p for interaction = 0.736 and 0.790), while no difference in bevacizumab-related AEs was observed in both subgroups (p for interaction = 0.566). In the overall population, as compared to younger pts, those aged 70-75 were more susceptible to overall G3/4 AEs (70% vs 57%, p = 0.001). In the FOLFOXIRI/bevacizumab arm a higher incidence of G3/4 diarrhea (27% vs 17%, p = 0.016) and febrile neutropenia (16% vs 6% p = 0.001) and a lower incidence of all grade nausea (51% vs 65%, p = 0.009) and vomiting (26% vs 44% p = 0.001) were reported among elderly pts. Conclusions: The activity and efficacy of FOLFOXIRI/bevacizumab are confirmed among selected pts between 70 and 75 years old, with a relative increase in the risk of chemo-related AEs similar to that of younger pts. However, elderly pts are more susceptible to experience AEs independently of the treatment arm. Considering the increased incidence of febrile neutropenia and diarrhea with FOLFOXIRI/bevacizumab, the use of G-CSF as primary prophylaxis or an initial dose reduction of irinotecan and 5-fluorouracil might be considered in this population.