Early retirement produces a heavy economic burden in many western societies. There is a need to identify single risk factors for early retirement and to find methods for preventing it. To estimate the effect of heavy physical work on early retiring, a cohort of 1755 men aged 42 to 65 years from eastern Finland was followed up from 1984 to 2000. Self-estimated physical workload was assessed at baseline. The inclusive pension records were obtained from national pension institutions. Logistic regression modeling was used to estimate the effect of physical workload and single physical risk factors on the risk of disability pension and nonillness-based pension. Risks were estimated for both disease-specific and all disability pensions. The interaction of physical fitness and physical workload and the resulting effects on risk were also estimated. During the follow-up, 861 (49.1%) men retired on a disability pension and 331 men (18.9%) retired on a nonillness-based early pension. Only 273 (15.6%) men reached the age for getting the normal old-age pension without having had any other early pension After adjustment for age, body mass index, alcohol consumption, smoking, maximal oxygen uptake, education and corresponding illness at baseline, heavy physical work was found to be associated with an increased risk of being retired on a disability pension due to musculoskeletal disorders (odds ratio (OR) 2.21, 95% confidence interval 1.36 to 3.61) but not due to cardiovascular or mental diseases. The association was stronger if cardiorespiratory fitness was poor. Lifting, static muscular loading and uncomfortable work positions increased the risk of early retirement especially due to musculoskeletal disorders. Loading of the upper extremity alone or with the neck and shoulder region seems to be an independent risk factor for early retirement. We concluded that physical workload increases the risk of retirement on a disability pension especially due to musculoskeletal disorders. In heavy physical work, the risk is increased especially among men with musculoskeletal or cardiovascular disease and poor cardiorespiratory fitness.