Forty students were randomly assigned into two study groups (traditional, T; and simulator, S) of 20 students each for a core operative practice laboratory. Students were randomly paired and their group assignment and identity remained anonymous to the evaluators throughout the study. Questionnaires were distributed to students to evaluate prior surgical experience and obtain learning resource use information. Before the evaluation sessions, both groups were given identical learning resource opportunities except students in Group S received hollow organ simulators and practice materials for gastrotomy closure. All students were forewarned that surgical instruction would not be available during the evaluation sessions. In the first live animal evaluation session, all student pairs were videotaped after which stomachs were harvested for gross evaluation of the surgical site. Group T performed an additional gastrotomy for video and gross evaluation 2 weeks later. Questionnaire, and gross and video evaluation results were compared statistically between groups and sessions. The hollow organ model did not suitably simulate live stomach tissue; the material was more fragile and stiff and suture cut-out was a problem even with appropriate suture tension and technique. The model was effective for teaching needle placement, instrument usage, creating proper tissue inversion, and methods to minimize instrument handling of tissue during gastrotomy closure. Prior practice with models did not boost student confidence during their live gastrotomy session. The autotutorials (ATs) were well received by students but did not sufficiently address how to manage mucosal eversion, suture tension, and bleeding encountered during live gastrotomy. AT viewing lime positively correlated with mean total video score for Group T during both sessions. None of the students had prior experience performing hollow organ closure and no significant difference in experience level was evident between groups. Mean closure time was not significantly different between groups for session one (Group T, mean, 31.5 minutes, range, 18.4 to 53.4; Group S, mean, 28.2 minutes, range, 16.8 to 36), but was significantly reduced for session two (Group T, mean, 21.3 minutes, range, 13.9 to 31). This AT/simulator program does not significantly influence students' overall gastrotomy closure technique; gross and video evaluation scores were not significantly different between groups. Without instructor supervision, an additional gastrotomy experience did not improve surgical technique appreciably for Group T; however, these students performed the second procedure with more confidence and speed. Instruction during simulator or live animal practice appears to be necessary to assure adequate skill mastery and to reduce perpetuation of mistakes.