Scrubbing, gowning, gloving and aseptic technique are currently the only formal teaching 4th year medical students receive at the beginning of an 8-week surgery rotation. Teaching is often delegated to junior house staff and early bad habits are difficult to unlearn in post-graduate training.A study population of 4th year medical students from three hospitals were examined. At the beginning of an 8-week surgery rotation technical skills were tested with a simulation appendectomy model at the beginning and end of the surgery rotation. On day one, after a pre-test, a teaching intervention was alternated between two hospitals. A control group received only a post-test. The outcome measure was a cumulative score of the students' performance in technical stations in the simulation model. A comparison was made of the mean post-test scores in the teaching, non-teaching and control groups.An analysis of variance of all post-test scores rejected the null hypothesis at the 0.05 level. Duncan's multiple range test demonstrated a significant difference between the teaching and non-teaching group. Feedback from 25 students indicated the teaching model was practical and relevant.A formal teaching intervention of basic technical skills with 4th year medical students improved their performance on a simulated appendectomy model.