Background: Necrotizing fasciitis is a rapidly progressive soft tissue infection with high morbidity and mortality rates. Examination of deep incisional biopsy specimens can provide prompt diagnosis and improve survival. We describe 7 patients with necrotizing fasciitis caused by group A Streptococcus species. Objective: Our purpose was to describe the unique dermatopathology and clinical features in 7 patients with necrotizing fasciitis caused by group A Streptococcus. Methods: We conducted a retrospective review. Results: The average age of the patients was 47 years. Fasciitis occurred on an extremity in all cases. All 5 patients with streptococcal toxic shock syndrome died of their disease. The histopathologic findings from early fascial disease revealed superficial epidermal necrosis, edema, and hemorrhage with few inflammatory cells, whereas clinically advanced, necrotic skin lesions revealed diffuse necrosis, thrombosis, neutrophilia, and numerous gram-positive diplococci. Conclusions: Patients with clinical features of necrotizing fasciitis should have a deep incisional biopsy specimen obtained from the central area of ecchymotic, necrotic plaques to confirm the diagnosis. Immediate surgical intervention is necessary to reduce the morbidity and mortality rates associated with necrotizing fasciitis. (J Am Acad Dermatol 2002;47:489-92.)