Background: Few studies have used simulation models to examine long-term improvement in microsurgical technique. We investigated whether improvement in surgical technique could be assessed by continuous, objective, contest-format evaluation of the same microsurgical task. Methods: Since 2014, neurosurgeons with 1-10 years of experience participated in a biannual competition-format test. The task involved creating as many sutures as possible during the 5-minute interval after arteriotomy of a 1-mm artificial vessel. A modified version of the Objective Structured Assessment of Technical Skills examination was created and used. Changes and differences in scores over time were examined for each evaluator. Results: Overall, 103 neurosurgeons participated in the study at least once, and those who participated more than once were divided into two groups: those who had the highest score in each contest and those who had the lowest score. The linear regression equations for the highest and lowest scorers were y=7.62x+81.56 (R²=0.628) and y=1.94x+67.93 (R²=0.0433), respectively. High scorers had high scores from the first time they participated, and their scores tended to increase further, while scores for low scorers tended not to increase with additional experience. Scores for the four evaluators did not significantly differ. Conclusions: Our results suggest that technical improvement in surgery can be assessed by long-term, continuous evaluation of microsurgical technique and that the present evaluation system might help increase surgical safety.