In a national cross-sectional study, the prevalence of neck/shoulder and low-back disorders and their relationship to work tasks and perceived psychosocial job stress was studied among forestry employees. The data were collected by occupational health service staff using Karasek's demand/control questionnaire for the psychosocial measures and the Standardized Nordic questionnaire for the analysis of musculoskeletal disorders. Based on data about past and present work tasks, the study population was classified into three groups: 645 manual workers, 66 machine operators and 124 administrative workers. Low-back disorders were more common among the manual workers than among the administrative workers [odds ratio (OR) = 1.98]. For the machine operators and manual workers, an increasing level of psychological demands was significantly associated with an increased prevalence of low-back disorders. The prevalence of neck/shoulder disorders was significantly higher among the machine operators (OR = 3.37) and manual workers (OR = 2.34) than among the administrative workers. An increasing level of psychological demands combined with a decreasing level of intellectual discretion was associated with an increased prevalence of neck/shoulder disorders. Authority over decisions was not associated with musculoskeletal disorders. In conclusion, musculoskeletal disorders were associated with both physical and psychosocial work factors. The modest strength of the associations between each individual independent variable and the outcome measure shows, however, that a substantial reduction in the prevalence of musculoskeletal disorders may be difficult to achieve. Nevertheless, the study clearly suggests that in the forestry industry attention should be paid to psychosocial work factors in future organizational changes and preventive programmes.