We analyzed data from 4,905 women aged 20-39 and 14,803 aged 40-49 who attended a health survey in Norway 1985-88, to study cardiovascular risk factors in users of oral contraceptives, all types and specifically by formulation. In age group 20-39, users of low-dose estrogen/ progestin regimens were younger, had lower body mass index (BMI), less often reported coronary heart disease in relatives, and less often used saturated fat on bread than did non-users. In age group 40-49, smoking was more prevalent in users of low-dose estrogen/progestin than in non-users. In both age groups the mean ratio of total/HDL cholesterol, the mean level of non-fasting triglycerides, and the mean systolic and diastolic blood pressures were higher in oral contraceptive users than in non-users. Among the users, a more favorable pattern was found in women using progestin-only oral contraceptives, as blood pressure levels were equal to those of non-users and total cholesterol and triglycerides were both 0.1-0.2 mmol/l below the non-users, in both age groups. However, users of low-dose estrogen formulations containing desogestrel 0.15 mg, norethisterone (norethindrone) 0.5 mg or lynestrenol 2.5 mg had the highest levels of HDL, even higher than the non-users. A pattern of higher triglycerides and higher ratio of total/ HDL cholesterol was found in smokers, compared with non-smokers, among users of any type of contraceptives, and in non-users.