INTRODUCTION The unplanned re-admission rate is a national key performance indicator employed by the UK Department of Health. An adjusted figure, based on admission information data on the hospital electronic Patient Administration System (PAS), but adjusted to take account of case mix is compared with a calculated 'expected'. While previous studies have investigated unplanned re-admission rates in age-, procedure- or process-specific conditions, 'all-cause' general surgical re-admission rate is yet to be studied. The aim of this study was to assess the accuracy of hospital unplanned re-admission data, and identify patterns or possible causes of unplanned general surgical re-admissions. PATIENTS AND METHODS Retrospective audit of case note records of all patients identified from the hospital electronic PAS as unplanned, general surgical re-admissions over a period of 4 consecutive months. RESULTS Of all 161 re-admissions in this study, 46 (29%) were unrelated to the index admission, planned or involved patient self-discharge during the index admission. Of the 'genuine', unplanned re-admissions, 80 (78%) followed an emergency index admission, 58 (56%) had chronic or recurrent symptoms, for which 26 (25%) were on waiting lists. Fourteen (14%) were multiple admissions of 4 patients, while 8 (8%) re-admissions required further surgery for significant postoperative complications. CONCLUSIONS Unplanned. general surgical re-admission rates collated from hospital PAS systems may be inaccurate. Nearly half of 'genuine', unplanned re-admissions involved patients with chronic and/or recurrent symptoms, which are predictable and may be preventable. Significant postoperative complications accounted for few re-admissions in this study.