This qualitative study investigated medical students' experiences of and conceptions concerning their professional development during their first clinical year. Twenty-two medical students participated in a portfolio course. Their personal writings were analysed by qualitative content analysis. Self-image as a future doctor rapidly evolved during patient contacts in the first clinical year. At the beginning, students felt lacking in credibility in front of their patients but towards the end they enjoyed their role as student-physicians. The medical students felt intense stress but the majority of this may stem from strong emotional experiences rather than the medical knowledge to be absorbed. Students were afraid of being humiliated by hospital staff and they felt themselves to be outsiders. No cynicism or suppression of feelings was observed in writings. The first clinical year is a period of intense emotional experiences and rapid development. Portfolios as learning tools may help in recognizing key experiences and in supporting professional development.