Background: Efforts to improve theatre efficiency aim to reduce health costs and maximize productivity. Operating lists in the private sector typically contain more cases than the public sector but it is unclear if this is a result of shorter operative times or reduced times between cases. We aimed to answer the question: Are operating times from skin incision to skin closure shorter in private compared to the public sector for total knee arthroplasty (TKA)? Method: The New Zealand Joint Registry was used to compare operating times for primary TKA performed for a diagnosis of osteoarthritis between the public and private sectors. Surgeries included were completed by surgeons who had performed more than 50 TKAs in both sectors. Multivariate analysis was used to control for other variables which may influence operative duration. Results: After adjustment for the variables of patient sex, age, American Society of Anesthesiologists score, body mass index and surgeon effect, a 3-min difference was present between the public and private sectors (public mean: 79.9 min versus private mean: 76.4 min (P < 0.05)).Conclusions: This study found minimal difference in operating time for TKA between the public and private sectors suggesting differences in overall theatre efficiency between the two sectors are not due to a shorter operative duration.