The purpose of this report is to survey the factors contributing to variation in lipoprotein(a) (Lp(a)) in a population-based sample of Anglo-Celtic Melburnians.The plasma Lp(a) levels were highly skewed towards low levels in this population, with a median of 156 mg/l and a mean of 262 mg/l. Approximately 33% had plasma Lp(a) above the threshold value of 300 mg/l, while 35% had Lp(a) levels below 100 mg/l. The most commonly occurring phenotype was apo(a) S3. In this phenotype, Lp(a) concentrations ranged from 10 to 596 mg/l. Lp(a) was consistently associated with diastolic blood pressure, systolic blood pressure, total protein, albumin and nitrogen excretion in the 40-60 y age group. Multiple stepwise regression analyses, in non-dietary factors, were used to explain about 13% of the variance in Lp(a) (19% in men and 23% in women). Remarkably, in the <40 y age group, non-dietary factors may account for 86% of the variance in Lp(a) and dietary factors, analysed separately, 46%. Thus, although Lp(a) is mainly genetically determined, there are clearly other factors which contribute to variations in Lp(a) concentrations.