Purpose <p>This study investigated whether the accuracy of 3D-guided osteotomies is influenced by surgeon experience. Two types of experience were assessed: (1) general surgical experience, defined as self-reported years in practice as an orthopaedic trauma surgeon, and (2) prior use of patient-specific guides (PSGs). Secondary aim was to evaluate whether accuracy varies by anatomical location.</p> Methods <p>24 orthopaedic-trauma surgeons performed 75 corrective osteotomies on cadaveric long-bones (43 single-cut, 32 double-cut; 107 cuts in total). Each osteotomy was preoperatively planned on CT-derived 3D-reconstructions, and PSGs were manufactured to guide the cuts. Postoperative CT-scans were used to compare planned and executed osteotomy planes. Surgeons completed a questionnaire reporting years of practice and annual PSG usage. A Spearman’s rank-order correlation was used to test differences in accuracy versus experience, a Kruskal-Wallis test was performed to explore differences across anatomical locations.</p> Results <p>General surgical experience ranged from 0 to 25 years (median 9), and PSG-usage from 0 to 20 cases annually (median 2). No association was found between general surgical experience and osteotomy accuracy (<i>p</i> = 0.406 and <i>p</i> = 0.548). In contrast, PSG-experience correlated with improved accuracy for angular and translational deviation of the osteotomy plane (<i>p</i> = 0.027 and <i>p</i> = 0.029). In addition, midshaft osteotomies of the lower extremity showed smaller angular deviations but larger translational errors compared with metaphyseal (<i>p</i> &lt; 0.001 and <i>p</i> = 0.003).</p> Conclusion <p>Experience with PSGs, rather than general surgical experience, improves accuracy in 3D-guided osteotomies, highlighting the need for training and repeated use. In contrast to metaphyseal, midshaft lower-extremity osteotomies are executed less accurately because fewer anatomical reference points are available.</p>