Background: Despite several publications strongly advocating prophylactic antibiotics during leech therapy, and recent primary articles shedding new light on the microbiota of leeches, many units either do not use antibiotic prophylaxis, or are continuing to use ineffective agents. Methods: A 5-year follow-up of plastic surgery units in the United Kingdom and the Republic of Ireland was conducted in 2007 to ascertain current practice regarding the use of prophylactic antibiotics with leech therapy. A comprehensive literature search investigated primary research articles regarding the microbiota of leeches to update the reconstructive surgery community. Results: Despite published evidence to support the use of prophylactic antibiotics during leech therapy, 24% of units do not use antibiotic prophylaxis and 57% of those using antibiotics are using potentially ineffective agents. Advanced molecular genetic techniques, which allow accurate characterization of both culturable and nonculturable microbiota of the leech digestive tract, show a wider diversity than at first thought, with variable antiobiotic resistance profiles. Conclusions: Despite infection due to leech therapy being a well known and relatively common complication, many units are not using appropriate antibiotic prophylaxis. © 2009 Wiley-Liss, Inc. Microsurgery 2009.