BACKGROUND: Racial and ethnic inequalities in colon cancer treatment have been reported in the United States but not elsewhere. The authors of this report compared cancer treatment in a nationally representative cohort of Maori (indigenous) and non-Maori New Zealanders with colon cancer. METHODS: On the basis of cancer registry data, 301 Maori patients and 329 randomly selected non-Maori patients were identified who were diagnosed with colon cancer between 1996 and 2003. Medical notes were reviewed, and surgical and oncology treatments were compared by indigenous status. RESULTS: Maori and non-Maori patients had similar rates of surgical resection, although Maori patients were less likely to undergo extensive lymph node clearance and were more likely to die during the postoperative period. Maori patients were significantly less likely to receive chemotherapy for stage III disease (relative risk [RR], 0.69; 95% confidence interval [CI], 0.53-0.91) and were more likely to experience a delay of at least 8 weeks before starting chemotherapy (RR, 1.98; 95%CI, 1.23-3.16). Treatment disparities were not explained by differences in tumor characteristics or patient comorbidity. CONCLUSIONS: Maori New Zealanders with colon cancer were less likely to receive adjuvant chemotherapy and experienced a lower quality of care compared with non-Maori patients. The authors concluded that attention to health system factors is needed to ensure equal access and quality of cancer treatment for indigenous and ethnic minority populations.