BACKGROUND: This study aims to investigate if a smartphone laparoscopy simulator, SimuSurg, is effective in improving laparoscopic skills in surgically inexperienced medical students. METHODS: This is a single-blinded randomized controlled trial featuring 30 preclinical medical students without prior laparoscopic simulation experience. The students were randomly allocated to a control or intervention group (n = 15 each) and 28 students completed the study (n = 14 each). All participants performed three validated exercises in a laparoscopic box trainer and repeated them after 1 week. The intervention group spent the intervening time completing all levels in SimuSurg, whereas the control group refrained from any laparoscopic activity. A prestudy questionnaire was used to collect data on age, sex, handedness, and experience with gaming. RESULTS: The total score improved significantly between the two testing sessions for the intervention group (n = 14, median change [MC] = 182.00, P = 0.009) but not for the control group (n = 14, MC = 161.50, P = 0.08). Scores for the nondominant hand improved significantly in the intervention group (MC = 66.50, P = 0.008) but not in the control group (MC = 9.00, P = 0.98). There was no improvement in dominant hand scores for either the intervention (MC = 62.00, P = 0.08) or control (MC = 26.00, P = 0.32) groups. Interest in surgery (β = -234.30, P = 0.02) was positively correlated with the baseline total scores; however, age, sex, and experience with video games were not. CONCLUSIONS: The results suggest that smartphone applications improve laparoscopic skills in medical students, especially for the nondominant hand. These simulators may be a cost-effective and accessible adjunct for laparoscopic training among surgically inexperienced students and clinicians.