Factors related to hand eczema were studied. Their relative importance as predictors was ranked by multiple logistic regression analysis. Questionnaires were sent to 20,000 individuals aged 20-65 years, randomly selected from the population register. Those subjects (1385) considering themselves to have had hand eczema within the previous 12 months were invited to a dermatological examination. It was found that a history of childhood eczema was the most important predictive factor for hand eczema. Second was female sex, followed by occupational exposure, a history of asthma and/or hay fever, and a service occupation. A small decrease in risk with advancing age was also found. The difference in the probability of having had eczema in a 1-year period, between individuals having the most important risk factors studied and those having none of them, proved to be for females 48% compared to 8%, and for males 34% compared to 4%. A history of childhood eczema was found to be more common among young persons, indicating an increase in the prevalence of atopic dermatitis. Of those individuals who reported childhood eczema, 27% reported hand eczema on some occasion during the last 12 months.