To define the efficacy and safety of maggot therapy, a cohort of 103 inpatients with 145 pressure ulcers was evaluated. Sixty-one ulcers in 50 patients received maggot therapy at some point during their monitored course; 84 ulcers in 70 patients did not. Debridement and wound healing could be quantified for 43 maggot-treated wounds and 49 conventionally treated wounds. Eighty percent of maggot-treated wounds were completely debrided, while only 48% of wounds were completely debrided with conventional therapy alone (p=0.021). Within 3 weeks, maggot-treated wounds contained one-third the necrotic tissue (p = 0.05) and twice the granulation tissue (p < 0.001), compared to non-maggot-treated wounds. Of the 31 measurable maggot-treated wounds monitored initially during conventional therapy, necrotic tissue decreased 0.2 cm(2) per week during conventional therapy, while total wound area increased 1.2 cm(2) per week. During maggot therapy, necrotic tissue decreased 0.8 cm(2) per week (p = 0.003) and total wound surface area decreased 1.2 cm2 per week (p = 0.001). Maggot therapy was more effective and efficient in debriding chronic pressure ulcers than were the conventional treatments prescribed. Patients readily accepted maggot therapy, and adverse events were uncommon.