PURPOSE: Combining several surgical procedures into one operative session is widespread in the field of plastic surgery; however, the implications of this practice are not fully understood. There are several benefits that should be taken into consideration when deciding whether to combine plastic surgery procedures. First, combining procedures reduces the number of times a patient must undergo anesthesia. Additionally, the patient benefits from a lower cost burden and single postoperative recovery. However, these benefits must be weighed against any potential increased risk for the patient. This study aimed to evaluate the rates and characteristics of adverse events associated with combining plastic surgery procedures in a single session as compared with similar outcomes of index procedures alone. METHOD: A retrospective cohort analysis was performed utilizing data between January 2016 and December 2020 from the TOPS database. The three most frequent combinations for each of the five most commonly performed plastic surgery procedures (augmentation mammaplasty, reduction mammaplasty, trunk liposuction, mastopexy, and abdominoplasty) were selected for analysis. The rate of 30-day adverse events, as defined by the TOPS database, served as the primary outcome. Chi-square analyses were to compare adverse event percentages. Chi-square, Kruskal-Wallis and Fisher’s exact tests were used as appropriate to compare patient characteristics. RESULTS: Of the total 35,157 patients analyzed, 12,373 (35%) underwent multiple concurrent procedures. Double or triple procedure combinations were found to have higher rates of 30-day adverse events compared to index procedures (8.7% and 7.7% compared to 4.2%, p<0.001, respectively). Rates of adverse events for double and triple procedure combinations remained elevated compared to index procedures throughout the five-year analysis (p<0.05). The 30-day adverse event rates were significantly higher for the three most common combinations for augmentation mammaplasty compared to index (4.3% and 2.3%, respectively, p<0.001), trunk liposuction combinations compared to index (13% and 2%, respectively, p<0.001), and reduction mammaplasty combinations compared to index (14% and 7.1%, respectively, p<0.001). Adverse events were not significantly different for the three most common combinations for mastopexy compared to index (4.7% and 4.5%, respectively, p=0.8), and abdominoplasty combinations compared to index (11% and 8.7%, respectively, p=0.066). A sub-analysis comparing patients coded for abdominoplasty, panniculectomy, or both was performed. Patients coded for both procedures had a higher rate of adverse events (12%) compared to abdominoplasty or panniculectomy alone (8.7% and 9.1%, respectively p=0.012). However, patients coded for panniculectomy alone were found to have the highest rates of diabetes (10%), hypertension (16%), and ASA class 5 status (9.2%) compared to patients coded for abdominoplasty alone or both procedures. CONCLUSION: The findings from this study help elucidate the impact of combining procedures. These results serve to inform shared surgical decision making in multi-procedure planning and contribute to patient safety.