The aim of our study was to identify the risk factors associated with the development of acute compartment syndrome (ACS) after a fracture of the tibia. Retrospective cohort study. Orthopaedic trauma unit, university teaching hospital. From our trauma database, we identified all patients who sustained an acute tibial diaphyseal fracture over a 13-year period. A retrospective analysis of 1407 patients was performed to record and analyze the OTA fracture classification, open fracture grade according to Gustilo, soft tissue injury classification according to Tscherne, treatment, development of ACS, and other patient demographics including smoking, occupation, and socioeconomic deprivation. A diagnosis of ACS was made using clinical signs, compartment pressure monitoring, or a combination of the 2. One thousand three hundred eighty-eight patients were included with a mean age of 39 (12-98) years, and 957 (69%) were male. One hundred sixty patients (11.5%) were diagnosed with ACS. On initial analysis, age, male gender, blue-collar occupation, sporting injury, fracture classification, and treatment with intramedullary nails were predictive of ACS (all P < 0.05). Age was the strongest predictor of developing ACS (P < 0.001), with the highest prevalence between 12-19 years and 20-29 years. Occupation (P = 0.01) and implant type (P = 0.004) were the only factors that remained significant after adjusting for age. On further subanalysis, implant type was not predictive when stratified by Tscherne class (P = 0.11). We have documented the risk factors for the development of ACS after an acute tibial diaphyseal fracture, with youth the strongest predictor. Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.