This paper concerns professional socialization of medical students. Professional socialization, in the context of this paper, means the process through which a layperson becomes a doctor equipped with professional identity and values. While medical education does not include such process in the curriculum, medical students obtain certain values and identity informally. The dependent variables were professional values and professionalism. The former means the desirable attributes required to conducting professional works such as humane attitudes, science-oriented mind, capability for organizational management. The latter means socio-political reasoning with which doctors can rationalize their privileges such as autonomy. A specially designed questionnaire was developed. The data were collected from five medical schools for 1,318 students in 1994. A total of 1,070 cases were finally included in the statistical analysis. The students emphasized the human factor in the professional values. Their attitude did not change with the grade. Other independent variables such as motives for entering a medical school, socioeconomic status, satisfaction with medical education, etc. also did not influence professional values. It implies that professional values were not consolidated among the students. However, the factors of professionalism change significantly with the grade. It implies that the students paid more attention to socio-political issues related to doctor`s interests as the grade went up. And the factor scores for professionalism were higher for those students who had more positive attitude towards doing medical practice for profit, expected higher income, and were more conservative about social reform. Other independent variables did not influence professionalism. It seems that the students also give emphasis on professionalism, like current medical doctors, mainly because of their concern with recent unfavorable changes in economic conditions of medical care providers.