The effect of ethnicity on the prevalence and presentation of polycystic ovarian syndrome (PCOS) was examined in a cross-sectional study of women with clinical - and ultrasound - diagnosed PCOS. European, Maori and Pacific Island women were seen in proportion to the general population, whereas Indian women were over-represented and Chinese women under-represented. European and Maori women were more likely to present with hirsutism than other ethnic groups (43% versus 25%, p < 0.05), while European women were less likely to present with infertility (46% versus 68%, p < 0.01). The Pacific Island women had little or no acne but other signs of PCOS were similar among ethnic groups. Although less than 10% of patients were referred with obesity, the majority of PCOS women were overweight on examination. Maori and Pacific Island women were more obese and had the highest rates of insulin resistance and lipid abnormalities. The adverse metabolic profile of many of these women, particularly the Maori and Pacific Islanders, is very likely to predispose them to early cardiovascular disease.