PIP: This is a cross-sectional study of the effects on carbohydrate and lipid metabolism in 316 women of oral contraceptives (OCs) given continuously for at least 2 years as compared with 358 women not on the pill. The 2 groups were matched for age, weight, height, and parity. The aim of this study was to ascertain whether any differences could be detected between different ethnic groups living in the same environment, and secondly, to examine the differences between OCs containing different progestogens. The mean duration of OC use was 61.3 months with a range from 32.4-90.2 months. OCs used were combined pills containing 50 mcg ethinyl estradiol. A total of 125 women were on pills containing the progestogen estrane and 170 were on Gonane. The remaining 21 women were taking a 17-OH-progesterone derived progestogen. Metabolic differences between Chinese and Malay women were not significant. For those women not on the pill, differences were minimal. Chinese women on OCs showed lower fasting plasma glucose values and this is a similar pattern in Western women. Malay women showed little change in fasting blood sugar. Judged by incremental glucose values, both Chinese and Malay women responded in exactly the same way to OCs; for plasma triglycerides and cholesterol, the metabolic effects of OCs seem to be greater in Chinese than in Malay women. The 19-nortestosterone and levonorgestrel pills appeared to have similar minimal effects on fasting and glucose values although insulin values after glucose were higher for levonorgestrel than for 19-nortestosterone; this suggests insulin resistance. The major difference between the 2 pills is seen in fasting plasma lipids. The relatively antiestrogenic progestagen levonorgestrel seems to effectively counteract hyperlipidemia seen in women using OCs containing a 19-nortestosterone progestogen. In general, the findings in this study closely parallel those seen in Western women.