OBJECTIVE: This study aimed to investigate the association between individual and psychosocial work factors and mental distress among offshore shift workers in the Norwegian petroleum industry. METHODS: All 2406 employees of a large Norwegian oil and gas company, who worked offshore during a two-week period in August 2006, were invited to participate in the web-based survey. Completed questionnaires were received from 1336 employees (56% response rate). The outcome variable was mental distress, assessed with a shortened version of the Hopkins Symptom Checklist (HSCL-5). The following individual factors were adjusted for: age, gender, marital status, and shift work locus of control. Psychosocial work factors included: night work, demands, control and support, and shift work–home interference. RESULTS: The level of mental distress was higher among men than women. In the adjusted regression model, the following were associated with mental distress: (i) high scores on quantitative demands, (ii) low level of support, and (iii) high level of shift work–home interference. Psychosocial work factors explained 76% of the total explained variance (adjusted R=0.21) in the final adjusted model. CONCLUSIONS: Psychosocial work factors, such as quantitative demands, support, and shift work–home interference were independently associated with mental distress. Shift schedules were only univariately associated with mental distress.