Blowfly maggots have been used in the treatment of wounds since antiquity. For more than ten years, advances in modern technology have enabled us to safely and widely apply larval therapy as one of the methods used to treat poorly healing ulcerations.The aim of the study was to determine the degree of non-healing wound debridement after the application of sterile Lucilia sericata blowfly maggots.Material and methods. The study group comprised 19 patients including 15 with crural ulcerations due to chronic venous insufficiency and four with diabetic feet. Each was subjected to larval therapy. Five patients were additionally diagnosed with advanced lower leg atherosclerosis. The study group comprised 12 female and 7 male patients between 48 and 86 years of age. The ulcerations were present for a period ranging between 1 and 420 months before the study. Twenty-one wounds were analyzed. The type and degree of vascular insufficiency of the lower legs was evaluated on the basis of Doppler ultrasound examinations utilizing the ankle/brachial index. Lucilia sericata blowfly maggots were placed in the wound, ten for every 1 cm2, and left for a period of 2-3 days. The external part of the dressing was changed 2-3 times per day. In addition to photographic documentation of the wound, swabs were collected for bacteriological examination before and after treatment.Results. The surface area of the wounds subjected to larval therapy ranged between 2 and 139 cm2. The mean surface area for venous ulcerations was 60 cm2, whereas, the mean for diabetic ulcerations was 47 cm2. The maggots were applied once to 9 wounds, twice to 4 wounds, three times to 4 wounds, four times to 3 wounds, and five times to one wound. Nine of the ulcerations were debrided from necrotic tissue by 90-100%, six by 70-90%, two by 55-60%, and three by 20-40%. In the case of one patient, the wound was not cleansed and the limb was amputated. Good biosurgical treatment results prevented three patients with diabetic feet from possible amputation at the level of the thigh (two patients), and lower leg (one patient). Debridement results were worse in patients where therapy was stopped due to acute pain (two patients) or significant bleeding (two patients), as well as in those with concomitant atherosclerosis.Conclusions. Biosurgical treatment of chronic lower leg ulcerations with the use of sterile Lucilia sericata blowfly maggots is a safe and effective method on the basis of debridement of wounds from necrotic tissue and purulent exudate.