Stigmatization towards mental illness is common both in society and healthcare personnel. This study aims to determine attitudes of medical students towards mental illness, the effective factors in their attitudes and to reveal their educational needs. The mixed model consisting of qualitative and quantitative methods was used to design the study. The study group of this cross-sectional research consisted of 744 2nd year and 5th year students, 21 healthcare personnel and 10 faculty working in psychiatry clinic in Medical Schools at Ankara University and Akdeniz University. Socio-demographic information form, stigma scales (Characteristics Scale, Affective Reaction Scale, Social Distance Scale) for alcohol-substance dependence, schizophrenia and depression, focus group discussion and individual interview methods were used to collect data. Stigma scales were applied on medical students and healthcare personnel. Four focus group discussions was conducted with the 5th year students and semi-structured individual interview was made with psychiatric faculty. Students' T-Test, ANOVA, Chi-square test and regression analysis were applied for quantitative data and content analyses were conducted for focus group discussions and individual interviews. It is observed that medical students have stigmatization tendency mostly to alcohol-substance dependence which is followed by schizophrenia and depression, respectively. "Characteristics Scale" scores of the 5th year students for alcohol-substance dependence and schizophrenia exhibit statistically less stigmatization than "Social Distance Scale" scores of the 2nd year students for depression. According to the regression analysis, variables related to stigmatization are gender (male), economic status of family (middle income), presence of mental ilness in family (not available), education period (2nd year) and having mental ilness (non available). Qualitative data indicated that "being diagnosed with mental ilness", "danger-uncertainty", "appearance", "affinity-relationship", and "belief and culture" are effective factors in attitudes of medical students towards mental ilnesss; their knowledge increase with psychiatry clerkship; however, their attitudes and behaviors do not change to a great extent. In light of the research findings, it can be recommended that a program which aims to enable students to achieve metacognitive and behavioral skills; to approach stigmatization in the context of humanism and patient-physician relationship; continues during medical education should be used in stigmatization education. Key words: Stigma, mental ilnesss, medical education [Anadolu Psikiyatri Derg 2015; 16(1.000): 22-29]