['The purpose of this study was to assess whether training to proficiency with the Fundamentals of Laparoscopic Surgery (FLS) simulator would result in improved performance in the operating room (OR).', 'Nineteen junior residents underwent baseline FLS testing and were assessed in the OR using a validated global rating scale (GOALS) during elective laparoscopic cholecystectomy. Those with GOALS scores <or=15 were randomly assigned to training (n = 9) or control (n = 8) groups. An FLS proficiency-based curriculum was used in the training group. Scoring on FLS and in the OR was repeated after the study period. Evaluators were blinded to randomization status.', 'Sixteen residents completed the study. There were no differences in baseline simulator (49.1 +/- 17 vs 39.5 +/- 16, P = .27) or OR scores (11.3 +/- 2.0 vs 12.0 +/- 1.8; P = .47). After training, simulator scores were higher in the trained group (95.1 +/- 4 vs 60.5 +/- 23, P = .004). OR performance improved in the control group by 1.8 to 13.8 +/- 2.2 (P = .04), whereas the trained group improved by 6.1 to 17.4 +/- 1.9 (P = .0005 vs control; P < .0001 vs baseline).'] Does fundamentals of laparoscopic surgery simulator training to proficiency improve laparoscopic performance in the operating room-a randomized controlled trial?