OBJECTIVE: To validate the cumulated ambulation score as an early postoperative predictor of short-term outcome in hip fracture patients. DESIGN: Prospective, descriptive study. SETTING: An orthopaedic hip fracture unit in a university hospital. PATIENTS: Four hundred and twenty-six consecutive hip fracture patients with an independent walking function admitted from their own home. Rehabilitation followed a well-defined multimodal rehabilitation regimen and discharge criteria. MAIN OUTCOME MEASURE: Admission tests with a new mobility score to assess prefracture functional mobility and a short mental score for cognitive dysfunction were performed. On the first three postoperative days patients were assessed with the cumulated ambulation score consisting of a cumulated assessment of simple ambulation characteristics with a score from 0 to 18 (fully mobile). The three assessments were correlated to short-term outcome parameters. RESULTS: The cumulated ambulation score was a highly significant predictor for length of hospitalization, time to discharge status, 30-day mortality and postoperative medical complications (P < 0.001 for all). The cumulated ambulation score was superior in its association with all postoperative outcome parameters to both the New Mobility Score and the mental score. A cumulated ambulation score of > or = 10 correlated with a 99% survival at one month and 93% discharge to own home. CONCLUSION: The cumulated ambulation score is a potentially valuable score for early prediction of short-term postoperative outcome after hip fracture surgery.