Chromium intake may increase insulin sensitivity, glucose tolerance, and the ratio of high density lipoprotein cholesterol to low density lipoprotein cholesterol. However, the epidemiologic evidence on the association between chromium and cardiovascular disease is very limited. To determine whether low toenail chromium concentrations were associated with risk of nonfatal myocardial infarction, the authors conducted an incident, population-based, case-control study in eight European countries and Israel in 1991-1992. Cases (n = 684) were men with a first diagnosis of myocardial infarction recruited from the coronary units of participating hospitals. Controls (n = 724) were men selected randomly from population registers (five study centers) or through other sources, such as hospitalized patients (three centers), general practitioners' practices (one center), or relatives or friends of cases (one center). Toenail chromium concentration was assessed by neutron activation analysis. Average toenail chromium concentrations were 1.10 mug/g in cases (95% confidence interval: 1.01, 1.18) and 1.30 mug/g in controls (95% CI: 1.21, 1.40). Multivariate odds ratios for quintiles 2-5 were 0.82 (95% CI: 0.52, 1.31), 0.68 (95% CI: 0.43, 1.08), 0.60 (95% CI: 0.37, 0.97), and 0.59 (95% CI: 0.37, 0.95). Toenail chromium concentration was inversely associated with the risk of a first myocardial infarction in men. These results add to an increasing body of evidence that points to the importance of chromium for cardiovascular health.