Background Hartmann's procedure is a commonly performed operation for complicated left colon diverticulitis or malignancy. The timing for reversal of Hartmann's is not well defined as it is technically challenging and carries a high complication rate. Methods This study is a retrospective audit of all patients who underwent Hartmann's procedure between 2008 and 2014. Reversal of Hartmann's rate, timing, American Society of Anesthesiologists grade, length of stay and complications (Clavien-Dindo) including 30-day mortality were recorded. Results Hartmann's procedure (n = 228) indications were complicated diverticular disease 44% (n = 100), malignancy 32% (n = 74) and other causes 24%, (n = 56). Reversal of Hartmann's rate was 47% (n = 108). Median age of patients was 58 years (range 21-84 years), American Society of Anesthesiologists grade 2 (range 1-4), length of stay was eight days (range 2-42 days). Median time to reversal of Hartmann's was 11 months (range 4-96 months). The overall complication rate from reversal of Hartmann's was 21%; 3.7% had a major complication of IIIa or above including three anastomotic leaks and one deep wound dehiscence. Failure of reversal and permanent stoma was less than 1% (n = 2). Thirty-day mortality following Hartmann's procedure was 7% (n = 15). Where Hartmann's procedure wass not reversed, for 30% (n = 31) this was the patient's choice and 70% (n = 74) were either high risk or unfit. Conclusions Hartmann's procedure is reversed less frequently than thought and consented for. Only 46% of Hartmann's procedures were stoma free at the end of the audit period. The anastomotic complication rate of 1% is also low for reversal of Hartmann's procedure in this study.