Women have higher long-term sickness absence rates than men, and higher rates of most health problems. The rates vary with type of problem and diagnosis. The objectives were to examine whether equal proportions of women and men had sickness absence when they had a given health problem, and if disparities were diagnosis specific. Prevalence of low-back pain, psychiatric disorders, and injuries was assessed in random samples of two populations in Norway. Prevalence of long-term sickness absence for the same diagnostic categories was estimated for the same time period (1990). For injuries, the prevalence ratios between a health problem and a sickness absence were equal for women and men. For psychiatric health problems, there were 1.7 more women than men behind each sickness absence. Low-back pain showed an intermediate gender ratio of 1.3, indicating that also for this condition women tended to have less sickness absence. Musculoskeletal and psychiatric health problems (fluctuating, chronic) may result in more gender-biased, subjective, and random assessment of work ability than injuries (acute health problem).