Elevated plasma lipoprotein(a) has been associated with an increased risk of cardiovascular disease. We report a significant elevation of total plasma apolipoprotein(a) levels in cancer patients compared with hospitalized control patients and normal healthy blood donors. Of the cancer patients studied, 48% had levels in excess of 350 mg/l compared to 20% in normal blood donors and 29% of hospitalized control patients. The elevation was more prevalent but less extreme than that reported in patients with cardiovascular disease. Density gradient centrifugation studies of plasma from cancer patients revealed the presence of apolipoprotein(a) at a density of 1.085 g/ml in the region where mRNA-containing proteolipids, neoproteolipids and malignancy-associated lipoproteins had previously been isolated.