Serum levels of total and high density lipoprotein (HDL) cholesterol and apolipoproteins A1 and B were measured in over 600 men and women aged 30-69 years who were selected at random from an Australian community. Total cholesterol and apolipoprotein A1 and B levels increased with age, with this effect being most pronounced for total cholesterol and apolipoprotein B in women. Body mass index and waist-to-hip ratio were positively correlated with apolipoprotein B and total cholesterol levels, and negatively correlated with apolipoprotein A1 and HDL cholesterol levels. All lipid and apolipoprotein A1 levels increased with the quantity of alcohol consumed. After adjusting for age, body mass index and smoking, the association with alcohol was strongest for apolipoprotein A1 and HDL cholesterol levels in men (P = 0.0001), and for apolipoprotein A1 levels in women (P = 0.01). Levels of apolipoprotein A1 and HDL cholesterol were lower, and of apolipoprotein B and total cholesterol were higher, in current cigarette smokers than non-smokers, with significant associations for apolipoprotein B (P = 0.004) and HDL cholesterol levels (P = 0.04) in men. In general, the associations between apolipoprotein A1 levels and the other variables were weaker than those for HDL cholesterol levels, whereas the associations with apolipoprotein B levels were stronger than those for total cholesterol levels (except for alcohol consumption). Thus, obesity, alcohol consumption and cigarette smoking should be considered when interpreting apolipoprotein levels.