Iron and copper catalyze lipid peroxidation in vitro, and recent epidemiological data suggest that these metal ions might also be involved in human coronary heart disease. We tested the hypothesis by investigating whether the storage proteins ferritin and ceruloplasmin were coronary risk factors. A nested case-control study was set up in middle-aged dyslipidaemic participants of the Helsinki Heart Study: a placebo-controlled coronary primary prevention trial with gemfibrozil. Of the 140 subjects with cardiac end-points (non-fatal myocardial infarction or cardiac death) 136 were matched with controls for geographical area and drug treatment (gemfibrozil-placebo). Frozen baseline serum samples were used in the analyses of ferritin and ceruloplasmin. Using logistic regression analyses no increment in coronary risk was detected with increasing ferritin levels (P = 0.8 for trend). Ceruloplasmin was higher 349 +/- 86 vs 317 +/- 77 mg.l-1 (P < 0.001) in cases than in controls and the risk in the highest tertile was two-fold (odds ratio 2.1; 95% CI 1.1-4.2) compared to the lowest (P < 0.005 for trend). The risk of high ceruloplasmin was influenced by lipoprotein cholesterol concentrations, with an odds ratio of 2.4 (95% CI 1.3-4.4) in subjects with high low density lipoprotein cholesterol and of 11.3 (95% CI 2.5-52.2) in subjects with low high density lipoprotein cholesterol. It was concluded that ferritin was not associated with coronary heart disease in dyslipidaemic, middle-aged men, while there was a continuous and graded increment in coronary risk with elevating ceruloplasmin level.