Skin and soft-tissue infections due to Pseudomonas aeruginosa were treated with intravenous infusions or intramuscular injections of cefsulodin sodium in an open, multicenter study. A total of 40 patients were evaluated to determine the safety and clinical and bacteriologic efficacy of cefsulodin. Cefsulodin was administered alone (31 patients) or in combination with a nonantipseudomonal antibiotic (nine patients) when additional infecting organisms were present. The duration of cefsulodin therapy ranged from two to 46 days (2-12 g/day). Twenty-five patients were treated at New Orleans hospitals for postoperative wound, traumatic wound, and skin ulcer infections with cefsulodin alone or in combination with nonantipseudomonal antibiotic. Therapy with cefsulodin (2-8 g/day) ranged from four to 37 days. P. aeruginosa was eradicated in all the patients, and all clinical responses were considered satisfactory. Fifteen patients were treated at the collaborative centers for postsurgical wound, traumatic wound, skin ulcer, cellulitis, and subcutaneous abscess infections. Therapy with cefsulodin (4-12 g/day) ranged from five to 45 days. The bacteriologic cure rate for assessable patients was 87% (13 of 15 patients), and a satisfactory clinical response was observed in 93% (14 of 15).