Anterior tibial compartment syndrome was developed due to pyomyositis in a 33-year-old male patient with rheumatoid arthritis while receiving steroid therapy during the follow-up period. The preoperative physical examination, laboratory findings, MRI images, intraoperative observation and postoperative histopathological examinations confirmed the association with pyomyositis. The surgical drainage and antibiotic treatment were effective, and in the follow-up period, neuromuscular dysfunctions disappeared completely within 6 months. The patient has been asymptomatic for 4 years of follow-up. To date, anterior tibial compartment syndrome due to pyomyositis in a case with rheumatoid arthritis has not been reported. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.