Currently, there are few reports regarding predictors of postoperative complications and short-term mortality after surgery for pathological femur fracture related to bone metastasis. Using data from the Japanese Diagnosis Procedure Combination Database from 2007 to 2012, we retrospectively identified 1497 patients who underwent internal fixation (n = 1073) or proximal femur resection and endoprosthetic reconstruction of the proximal femur (n = 424) for pathological femur fracture related to bone metastasis. Multivariable logistic regression analysis was performed to examine the relationship of various factors with postoperative complications and 30-day mortality. The overall 30-day mortality after surgery was 2.6 %, and the proportion of postoperative complications was 12.1 %. Multivariable logistic regression analysis showed that postoperative complications overall were significantly associated with older age [odds ratio (OR), 2.15; 95 % confidence interval (CI) 1.23–3.74 for age ≥80 vs. ≤59 years]; lung carcinoma (OR 2.05; 95 % CI 1.47–2.86); esophageal carcinoma (OR 4.41; 95 % CI 1.57–12.43); higher Charlson Comorbidity Index (OR 1.50; 95 % CI 1.03–2.18 for ≥9 vs. 8); and blood transfusion (OR 1.57; 95 % CI 1.14–2.15). Thirty-day mortality also was significantly higher in patients with rapid-growth tumors, visceral metastasis, internal fixation, and no postoperative chemotherapy in the univariate analysis. Older age, type of primary tumor, higher Charlson Comorbidity Index, and blood transfusion were associated with higher morbidity. These findings can provide important information to assess perioperative risk in patients with pathological femur fracture related to bone metastasis.