The optimal timing of contralateral surgery following unicompartmental knee arthroplasty (UKA) remains unknown. Therefore, the objective of this study was to examine the differences in postoperative complications in patients undergoing unilateral, simultaneous, and staged bilateral UKA.The PearlDiver administrative claims database was queried for patients undergoing UKA between 2015 and 2020. Patients undergoing unilateral UKA were matched in a 1:1 fashion with patients undergoing simultaneous bilateral UKA, staged bilateral UKA within 1 to 90 days, and staged bilateral UKA within 91 to 365 days based on age, gender, Elixhauser Comorbidity Index (ECI), obesity, diabetes, and smoking status. Univariate and multivariate analyses were performed to examine the impact of timing of bilateral procedures on 90-day postoperative complications relative to patients who underwent unilateral UKA. Outcomes were considered significant at