Background: One of the priorities of research in education is study about the causes of students failure during their academic work Objective: To investigate the causes of students academic failure and probation Methods: In this casecontrol study 761 volunteer students in Hamadan University of Medical Sciences during fall and spring semesters of 20012002 were participated Students were divided into two groups Case group consisted of 43 students who had academic failure leading to their probation and control group consisted of 718 students who were successful in their study program Data collection was done by a questionnaire designed based on eight main factors in learning process including: method of teaching evaluation educational materials planning for the semester courses personal characteristics environmental problems academic environment and accessibility of academic advisors The questionnaire was used after reliability and validity evaluation Results: The percentage of academic probation was higher in boys (94%) compared to girls (43%) Among eight factors affecting learning process there was a significant difference (P= 0014) between the two groups in their mean score of opinions about the method of teaching (356 ± 116 in the case group vs 359± 098 in the control group) There was also significant difference between the two groups in regard to mean score of the personal characteristics (436 ± 126 in case group vs 476 ±108 in control group P= 0023) The obtained mean scores for method of teaching and personal characteristics of the students was significantly higher according to the students who had a score below 10 for at least 1 course Mean scores of method of teaching and environmental & educational problems were significantly higher according to the students who had a score between 1012 in at least one course (P