Ethical behavior and professionalism is an ideal characteristic required of medical students and included as ‘must achieve’ and critical aspect of medical students’ curriculum. This study proposes to determine the perceived unethical and unprofessional behavior among medical students in a private medical university from year 1 to year 5 of the medical curriculum. A cross–sectional study was conducted among year 1 to year 5 medical students in a private medical university. A self-administered questionnaire was used with the 3 major domains of professionalism and ethics i.e. discipline plagiarism and cheating. A total of 464 respondents responded to the survey and they included medical students from year 1 and year 2 (pre-clinical) and years 3–5 (clinical years). Majority of the students, 275 (59.2%) answered that they had not seen any form of unethical behavior among other students. The females seem to have a larger number 172(63%) among the same gender compared to the males. Majority 352 (75%) of them had not heard of the ‘Code of Professional Conduct by the Malaysian Medical Council’. About fifty three (53.1%) of the students answered that the training was sufficient. This study showed that the perception of unethical behavior was 58.8% in the 1st year (pre-clinical) and it increased to 65.2% in the 5th year (clinical). The 3 main discipline issues were students do not show interest in class (mean 2.9/4), they are rude to other students (mean 2.8/4) and talking during class (mean 2.6/4). Despite the existence of unethical behavior among the students majority of them (71.7%) claimed that they had adequate training in ethics and professionalism. It is proposed that not only the teaching of ethics and professionalism be reviewed but an assessment strategy be introduced to strengthen the importance of professionalism and ethics.