Research observations suggest an increase in distress during the course of medical education, but it is not known whether this distress is chronic and persistent or episodic because follow-ups covering the whole training programme are lacking. We explored stress symptoms among undergraduate medical students (n = 110) at five points during the six-year medical training programme. The quality and continuity of symptoms and gender differences in stress reports were analysed. Questionnaire and interviews were used to assess stress symptoms, perceived health and severity of distress. Stress symptoms, such as fatigue, sleeping problems, anxiety, irritability and depression, were common. No significant gender differences were seen, but there was a consistent increase of stress reports throughout the medical programme in both sexes. Those who were most distressed at the beginning of training also reported more stress later. To conclude, we need interventions that help students to cope with stress, to make a smooth transition from school to medical school, and also to adjust to different learning environments during the different phases of medical education.