Hospital readmission is a key surgical quality metric associated with financial penalties and greater healthcare costs. We examined the clinical risk factors and postoperative complications associated with 30-day unplanned hospital readmissions after cranial neurosurgery.We queried the American College of Surgeons National Surgical Quality Improvement Program database from 2011 to 2016 for adult patients who had undergone a cranial neurosurgical procedure. Multivariable logistic regression with backward model selection was used to determine the predictors associated with 30-day unplanned hospital readmission.Of 40,802 cranial neurosurgical cases, 4147 (10.2%) required an unplanned readmission. Postoperative complications were greater in the readmission cohort (18.5% vs. 9.9%; P0.001). On adjusted analysis, the clinical factors predictive of unplanned readmission included hypertension, chronic obstructive pulmonary disease, diabetes, coagulopathy, chronic steroid use, and preoperative anemia, hyponatremia, and hypoalbuminemia (P ≤ 0.01 for all). Higher American Society of Anesthesiology class (III to V), operative time216 minutes, and unplanned reoperation were also associated with an increased likelihood of readmission (P ≤ 0.001 for all). The postoperative complications predictive of unplanned readmissions were wound infection (odds ratio [OR], 4.90; P0.001), pulmonary embolus (OR, 3.94; P0.001), myocardial infarction or cardiac arrest (OR, 2.37; P0.001), sepsis (OR, 1.73; P0.001), deep venous thrombosis (OR, 1.50; P = 0.002), and urinary tract infection (OR, 1.45; P = 0.002). Female sex, transfer status, and postoperative pulmonary complications were protective of readmission (P0.05 for all).Unplanned hospital readmission after cranial neurosurgery is a common event. The identification of high-risk patients who undergo cranial procedures might allow hospitals to reduce unplanned readmissions and their associated healthcare costs.