The aim of this study was to examine the rates and potential risk factors for 28-day re-admission following a fracture of the hip at a high-volume tertiary care hospital. We retrospectively reviewed 467 consecutive patients with a fracture of the hip treated in the course of one year. Causes and risk factors for unplanned 28-day re-admissions were examined using univariate and multivariate analysis, including the difference in one-year mortality. A total of 55 patients (11.8%) were re-admitted within 28 days of discharge. The most common causes were pneumonia in 15 patients (27.3%), dehydration and renal dysfunction in ten (18.2%) and deteriorating mobility in ten (18.2%). A moderate correlation was found between chest infection during the initial admission and subsequent re-admission with pneumonia (r = 0.44, p < 0.001). A significantly higher mortality rate at one year was seen in the re-admission group (41.8% (23 of 55) vs 18.7% (77 of 412), p < 0.001). Logistic regression analysis identified advancing age, admission source, and the comorbidities of diabetes and neurological disorders as the strongest predictors for re-admission. Early re-admission following hip fracture surgery is predominantly due to medical causes and is associated with higher one-year mortality. The risk factors for re-admission can have implications for performance-based pay initiatives in the NHS. Multidisciplinary management in reducing post-operative active clinical problems may reduce early re-admission.