IgA nephropathy (IgAN) accounts for a far higher proportion of end-stage renal disease (ESRD) in Asia compared with North America. It is not known whether this is entirely because of differences in disease prevalence or a higher risk of disease progression. The lack of a racially diverse population cohort followed longitudinally has previously precluded the ability to address this question. To determine whether Asians in North America with IgAN are at higher risk for ESRD, we analyzed a cohort of 202 patients of self-reported Pacific Asian origin and 467 of other origin from the Toronto GN Registry followed up for a median of 46.4 months. The primary outcome of ESRD (dialysis, transplantation, or eGFR below 15) was analyzed using Cox regression analysis. Baseline eGFR was 59.6 ml/min/1.73 m(2), and median proteinuria was 1.8 g/day. ESRD occurred in 213 patients. By univariable analysis, the risk of ESRD was similar between the two groups (hazard ratio 0.98, 95% CI 0.73, 1.31); however, after adjusting for age, gender, eGFR, medication use, blood pressure, and proteinuria, the risk of ESRD was significantly higher in Pacific Asian individuals (hazard ratio 1.56, 95% CI 1.10, 2.22). This was supported by a significant 1.62 ml/min/1.73 m(2)/year faster rate of eGFR decline (95% CI -3.19, -0.5) and an increased risk of a reduction in eGFR by half (hazard ratio 1.81, 95% CI 1.25, 2.62). Thus, in a large multiracial cohort of patients with IgAN, individuals of Pacific Asian origin have a higher risk of progression to ESRD.