Cigarette smoking is known to accelerate decline of pulmonary function; however, the role of other factors is less clear. Characteristics of individuals who experienced rapid decline in forced expiratory volume in 1-sec (FEV1) were examined in 4451 Japanese-American men from the Honolulu Heart Program who were aged 45 to 68 years at baseline (1965-1968) and who produced three acceptable FEV1 measures over a 6-year period. Average annual rates of FEV1 decline were calculated by use of within-person regression and were categorized as rapid (> or = 60 ml/y), moderate (30 to 59 ml/y) or slow (< 30 ml/y). Lifestyle and biologic factors were compared by FEV1 decline categories after adjustment for age. A logistic regression model showed that continued smoking during follow-up, cigarette pack-years, wheezing, coronary heart disease, alcohol intake, and reduced subscapular skinfold were significantly associated with rapid FEV1 decline, after adjustment for age, height, cholesterol, an indicator of Japanese diet, and education. When analyses were restricted to continuous smokers, cigarette pack-years, wheezing, and reduced subscapular skinfold were found to be independent predictors. Among never smokers, lower educational attainment was a predictor of rapid FEV1 decline, and the association involving subscapular skinfold approached significance (P < 0.07). These characteristics may be useful in identifying subgroups of the population who are at increased risk of accelerated decline in pulmonary function and thus would be most likely to benefit from appropriate intervention.