In the United States population, black men have higher prevalence rates of electrocardiographic (ECG) high QRS voltage, more ST-segment and T-wave abnormalities, and more ECG left ventricular hypertrophy (LVH) than do white men. Reasons for these differences have not been fully elucidated. The prevalence rate of ECG LVH and associated characteristics were compared in black and white men in the Chicago Heart Association Detection Project in Industry population study. Data were from 1,391 black men and 19,126 white men (age range 20 to 64 years) employed by 84 Chicago organizations. ECG LVH was defined by the presence of both high QRS (Minnesota code 3.3) and ST-T abnormality (code 4.1-4.3 or 5.1-5.3). Black men had a significantly higher prevalence rate of ECG LVH than did white men in each 15-year age group (15.9 vs 2.4, 14.6 vs 2.8, and 35.7 vs 12.5/1,000 in the 20- to 34-, 35- to 49-, and 50-to 64-year age groups, respectively; p < 0.01 for each comparison). Multiple logistic regression analyses indicated that systolic blood pressure and age were associated positively with ECG LVH (p < 0.01) in both black and white men. Men with history of hypertension and receiving drug treatment had a greater likelihood of having ECG LVH than did those with history of hypertension but not receiving drug treatment, possibly because those with more severe hypertension were more likely to have been prescribed medication. Serum cholesterol, cigarettes smoked/day, 1-hour post-load plasma glucose and education were not consistently related to ECG LVH.(ABSTRACT TRUNCATED AT 250 WORDS)