Stress has been recognized one of the factors causing disease. About 70-80% of all diseases may be stress related. Thus, stress management can be a part of an early measure of disease prevention. A descriptive cross sectional, randomized study was conducted to determine the stress inducing factors among preclinical students (universal sampling) in a public university in Selangor, Malaysia from 24th April to May 2005. A total of 163 students (52.8% year 1, 36.8% year 2 and 10.4% year 3) were interviewed in the data collection process. The main reasons students entered - medical school was because of their own interest or ambition (65%) and family influence (20.9%). Majority (76.4%) suffered moderate to great stress over hot conditions in lecture hall, tutoriaV small group session rooms and laboratories while 53.4% suffered when using the other facilities like cafeteria, toilet and transportation:. Almost all (95.1%) felt that examination was the most stressful, followed by early clinical exposure sessions (68.1%), problem·based learning sessions (62.5%), hospital visitations (59.7%), tutoriay small group sessions (49.3%), practical class (44.5%) and attending lectures (3 8.5%). Musculoskeletal System was the most stressful module among the first year students, followed by Nervous System and Gastrointestinal System with the percentage of 94.2%, 90.7% and 88.4% respectively while, 95% of the second year students felt that General, Hemopoietic ci? Lymphoid and Nervous System are the most stressful modules. This study revealed that academic sessions and lack of conducive teaching and learning environment as the main stress inducing contributors to preclinical medical students.