Eighty-four Chinese patients attending the Family Planning Association of Hong Kong for contraception with oral contraceptive pills were randomized into 2 groups. The first group received pills containing 0.15 mg levonorgestrel and 0.03 mg ethinyl oestradiol. The second group received pills containing 0.15 mg desogestrel and 0.03 mg ethinyl oestradiol. Blood was taken after overnight fast before the use of pills for assay of serum total lipids, triglycerides, total cholesterol and high density lipoprotein cholesterol (HDL-C). The tests were repeated at 1 month, 3 months and 6 months after the use of pills. There was a significant increase in the serum total lipids in the levonorgestrel group but not in the desogestrel group. The serum triglycerides showed a significant increase in the desogestrel group but not in the levonorgestrel group. There was no significant change in the serum total cholesterol levels in both groups. There was a significant decrease in the HDL-C in the levonorgestrel group but there was no significant change in the desogestrel group.