Group A streptococci produce a variety of clinical symptoms ranging from minor pharyngeal infections to life-threatening soft-tissue disease. A rabbit model is described for induction of myonecrosis and fasciitis with group A beta-hemolytic streptococci. Group A streptococcal infections have shown remarkable virulence in recent years, resulting in severe local tissue destruction and life-threatening toxicity. After subcutaneous injection into the thigh of 20 ml broth containing 10(5) to 10(9) cfu/ml, initial soft tissue infection rapidly progressed to rhabdomyolysis. The response of the rabbits to the infection was consistent with the human response.