Objective: The aim of our study is to find out the predictors of TOT in RALM. It will help selecting an adequate patient pool, enhancing preoperative counseling, optimizing operation schedule, and systemizing the intraoperative preparation process, thus improving the perioperative outcomes and patients’ satisfaction. Methods: We conducted a retrospective cohort study of women undergoing RALMs between April 2009 and May 2019 by a single high-volume gynecologic surgeon at the Seoul St. Mary’s hospital. Cases that were performed concomitantly with any other surgical procedure were excluded. Demographic data and intraoperative records were obtained. The association between the number, size, location, FIGO type of myoma and TOT was analyzed. Results: A total of 616 cases met our criteria, with a mean TOT of 234 ± 88 minutes. The mean age of patients was 36.0 ± 5.4. The mean number of myomas removed was 4.2 ± 4.0 and mean largest myoma diameter was 7.7cm ± 2.6cm. Mean total weight of myoma removed was 201.4 ± 151.7g. Only one patient underwent conversion to laparotomy. Preoperative factors intimately associated with TOT were identified with the multiple regression analysis. TOT prolonged as the number of myoma increases (β = 11.69, P < 0.0001) or total myoma weight increases (β = 0.18, P < 0.0001). If the endometrial cavity was exposed during the operation, longer surgery time was needed (β = 23.62, P = 0.002). Age, parity, body mass index, personal history of hypertension and diabetes mellitus, previous abdominal surgery, surgical indication, location of dominant myoma and classification of dominant myoma were not associated with TOT. Conclusion: In this study, we found the total number of myomas, myoma weight, and exposure of endometrial cavity to be significantly correlated to TOT of RALM.