During the past two decades there has been a resurgence of invasive group A streptococcal (GAS) infection, specially pneumonia and bacteremia. We report a 35 year-old female previously subjected to a thyroidectomy for a thyroid cancer, that five days after operation, presented with a severe community-acquired pneumonia caused by Streptococcus pyogenes (Lancefield Group A Streptococcus) that was complicated by acute respiratory failure and septic shock. She was treated with a combination of 3 g/day of cefotaxime and 1.8 g/day of clindamycin with a good clinical response and discharged from the hospital in good conditions. Although this microorganism is an uncommon cause of community-acquired pneumonia, previously healthy individuals may be infected and the clinical course may be fulminant. Patients with invasive GAS infection admitted to ICU have a high mortality rate. Treatment of choice of Group A streptococcal infection is penicillin. However, clindamycin should be added in severe infections .