Background: Despite an increased risk of suicide among physicians Lye lack studies on prevalence and predictors of suicidal ideation among medical students and young doctors. Method: A prospective study of Norwegian medical students (n = 522) re-examined after the first postgraduate year. comprising suicidal thoughts and attempts, perceived study str ess, job stress, and personality. Results: The previous year prevalence of suicidal thoughts was 14% at both points of time. The lifetime prevalence was 43%, while 8% had planned suicide, and 1.4% had attempted suicide. Suicidal ideation in medical school was predicted by lack of control, personality trait, single marital status, negative life events and mental distress (anxiety and depression). In the first postgraduate year, mental distress was the most important predictor, but before controlling for this variable, job stress, vulnerability (neuroticism), single status, and less working hours were independent predictors. Prospectively, suicidal thoughts and vulnerability as student predicted postgraduate suicidal ideation. Conclusions: The level of suicidal thoughts was high, but 1the level of attempts was low. Clinical implications: Preventive efforts should be directed both at the students' abilities to cope with stress and at mental health services for young doctors. Limitations of study: The lower response rate at follow-up (57%) may reduce external validity. (C) 2001 Elsevier Science B.V. All rights reserved.