Piperacillin/tazobactam (P/T) or tazocin was used in the treatment of 40 patients with soft tissue purulent necrotic wounds of various genesis and localization. In the majority of the patients the affection was of recurring nature. P/T was administered in a dose of 4.5 g 3 times a day for 1 to 14 days (mainly for 8 to 10 days) as 30-minute intravenous infusions. The clinical effect of the treatment was stated in 36 patients (90 per cent). In 3 out of 8 patients with diabetes mellitus the treatment failed. In 1 patient the treatment was discontinued after the first dose because of asphyxia and a short-term decrease of the arterial pressure. Among 105 microbial strains isolated from 75 patients 64 were highly susceptible to P/T, 33 were moderately susceptible and 8 were resistant. 76.3 per cent of the isolates produced beta-lactamase, 66.3 per cent of them were susceptible to P/T. 54 gram-positive and gram-negative strains were isolated from 40 patients. 16 out of the 54 strains were isolated as monocultures and the others as associations. After the treatments the pathogen eradication and the pathogen eradication followed by superinfection were stated in 26 patients (66.7 per cent). In 11 patients (28.2 per cent) the pathogen persistence was observed at the background of the clinical improvement in the majority of the patients. The relapses were recorded in 2 patients (5.1 per cent).