OBJECTIVES. OPTIMOX1 randomised study demonstrated that FOLFOX7 with oxaliplatin stop-and-go could be safely used and achieved the same efficacy results as standard treatment FOLFOX 4 in advanced colorectal cancer. The median progression free-survival and survival times were 9.0 and 19.3 months, respectively in FOLFOX4 arm compared with 8.7 and 21.2 months, respectively in FOLFOX7 arm (p=not significant). FOLFOX 7 stop and go strategy was associated with reduced risk of grade 3 to 4 toxicity [Tournigand, JCO 2006; 24:394]. The main objective was to perform an economic evaluation of FOLFOX7 stop-and-go compared with FOLFOX4 regimen in advanced colorectal cancer. METHODS. A cost-minimisation analysis has been conducted based on the efficacy results of OPTIMOX1 study. The perspective was that of the third party payer and included only direct medical costs: chemotherapy, hospitalisation and side effects management. The horizon time was from inclusion until patient death. Sensitivity analyses were performed on drug costs and full/day hospitalisation rates. RESULTS. Hospitalisation costs per patient were the main driver for cost. Hospitalisation represented €6,595 in FOLFOX7 arm vs. €10,522 in FOLFOX4 arm reflecting the decrease of number of hospitalisation days (p<0.001). Chemotherapy costs per patient were comparable in each treatment arm despite higher doses of oxaliplatin with FOLFOX7 (€6,870) compared to FOLFOX4 (€7,047) (p=0.30). The cost of side effects management appeared very low in both groups, compared to hospitalisation and drug costs with €271 and €382 (p=0.11) for FOLFOX4 and FOLFOX7 respectively. The mean total cost per patient was higher in FOLFOX4 arm than in FOLFOX7 arm with €17,841 versus €13,847 respectively (p<0.001). CONCLUSION. The FOLFOX7 regimen with intermittent oxaliplatin treatment (stop-and-go) is cost saving compared with FOLFOX4 regimen.