Aims <p>Reconstruction of bone defects is a key challenge in orthopaedic surgery. While autologous bone grafts are considered the gold standard, osseous allografts are increasingly used as an alternative as they allow for treatment of large bone defects. However, they may be associated with an increased risk of postoperative infections. This study aims to analyze the frequency of and risk factors for implant-associated infections after bone allograft transplantation.</p> Methods <p>All patients who underwent reconstruction with bone allografts at a single orthopaedic and trauma unit between 2003 and 2023 were retrospectively included. Data on demographics, disease-associated parameters, risk factors at index surgery, and development of implant-associated infections during follow-up were documented. Potential risk factors for development of implant-associated infections during follow-up were investigated with logistic regression models.</p> Results <p>A total of 220 patients were included (46.8% males; median age at surgery 46.5 years [IQR: 22–67]; <i>n</i> = 23 with implant-associated infections during follow-up). Factors independently associated with subsequent implant-associated infections were smoking (<i>p</i> = 0.001), BMI (<i>p</i> = 0.015) and radiotherapy (<i>p</i> = 0.013). Gender, age, preoperative chemotherapy, allograft material, preoperative C-reactive protein, hemoglobin and reason for surgery (tumor, <i>n</i> = 104; trauma, <i>n</i> = 13; revision, <i>n</i> = 103) were not associated with implant associated infection.</p> Conclusion <p>Independent risk factors for implant-associated infections following bone allograft surgery included active smoking, high BMI and radiotherapy (in case of tumor). These factors should be taken into consideration when planning bone allograft reconstruction.</p>