Background Stigma and discrimination toward mentally disabled persons might exist within the medical environment and may form a barrier for patients to receive appropriate care. The aim of this study is to determine the attitudes of medical students toward mentally disabled people and to understand the impact of schooling on attitude difference by evaluating second and sixth year medical students. Method The study was carried out among 452 students from all the three public medical schools located in Istanbul, Turkey. Attitudes were assessed through a Likert scale by presenting vignettes for depression and schizophrenia. Results In both men and women, the scores of last year students for depression and schizophrenia scales were better compared with those of the second graders, and the differences were statistically significant (p < 0.05). However, the proportion of students who did not perceive schizophrenia as "temporary" and "curable" and the perceived likelihood of dangerousness for schizophrenia were higher among the last year students compared with the second graders. Conclusion As a result of this study, it was determined that last year students had improved attitudes toward the mentally ill; however, they still had striking stigmatizing opinions and judgments. The improvement in the attitude score between the second and the sixth graders is considered a result of the students' contact and interaction with persons having mental disorders throughout their medical education. The challenge is to maintain a social environment that aims to reduce the distance between the patient and the medical staff through introducing a holistic approach in medical schools.