AIMS: This study evaluated variation in the surgical treatment of stable (A1) and unstable (A2) trochanteric hip fractures among an international group of orthopaedic surgeons, and determined the influence of patient, fracture, and surgeon characteristics on choice of implant (intramedullary nailing (IMN) versus sliding hip screw (SHS)). METHODS: A total of 128 orthopaedic surgeons in the Science of Variation Group evaluated radiographs of 30 patients with Type A1 and A2 trochanteric hip fractures and indicated their preferred treatment: IMN or SHS. The management of Type A3 (reverse obliquity) trochanteric fractures was not evaluated. Agreement between surgeons was calculated using multirater kappa. Multivariate logistic regression models were used to assess whether patient, fracture, and surgeon characteristics were independently associated with choice of implant. RESULTS: The overall agreement between surgeons on implant choice was fair (kappa = 0.27 (95% confidence interval (CI) 0.25 to 0.28)). Factors associated with preference for IMN included USA compared to Europe or the UK (Europe odds ratio (OR) 0.56 (95% CI 0.47 to 0.67); UK OR 0.16 (95% CI 0.12 to 0.22); p < 0.001); exposure to IMN only during training compared to surgeons that were exposed to both (only IMN during training OR 2.6 (95% CI 2.0 to 3.4); p < 0.001); and A2 compared to A1 fractures (Type A2 OR 10 (95% CI 8.4 to 12); p < 0.001). CONCLUSION: In an international cohort of orthopaedic surgeons, there was a large variation in implant preference for patients with A1 and A2 trochanteric fractures. This is due to surgeon bias (country of practice and aspects of training). The observation that surgeons favoured the more expensive implant (IMN) in the absence of convincing evidence of its superiority suggests that surgeon de-biasing strategies may be a useful focus for optimizing patient outcomes and promoting value-based healthcare. Cite this article:  2021;103-B(4):775-781.