The MOSAIC study was the first trial to show a statistically significant disease-free survival benefit for a treatment regimen for stage III colon cancer in the adjuvant setting. At 4 years, there was a 25% reduction in the risk of disease recurrence in these patients for the combination of oxaliplatin/5-FU/FA compared with 5-FU/FA alone (p=0.002). This analysis evaluates the long-term cost effectiveness of oxaliplatin given in combination with 5-FU/FA from the perspective of the NHS in the United Kingdom (UK). The cost per quality-adjusted life-year gained over a lifetime was calculated using patient level data from the MOSAIC trial. Trial data were available for a median of 4 years of follow-up, these data were then extrapolated to a lifetime horizon. The estimated incremental lifetime cost per quality-adjusted life-year of oxaliplatin/5-FU/FA compared with 5-FU/FA alone in patients with stage III postoperative colon cancer is pound 4805. This compares favourably with other accepted interventions in oncology.