Ignaz Semmelweiss made one of the most important contributions to modern medicine when he instituted handwashing in an obstetric clinic in Austria in 1847, decreasing mortality there from more than 10% to 2%. Unfortunately, puerperal sepsis remains a leading cause of maternal mortality throughout the world. Group A streptococcus (GAS), Streptococcus pyogenes, is an organism associated with high rates of morbidity and mortality from puerperal infections. When associated with sepsis, known as streptococcal toxic shock syndrome, mortality rates approach 30–50%. Group A streptococcus can cause invasive infections in the form of endometritis, necrotizing fasciitis, or streptococcal toxic shock syndrome. The clinical presentation of women with puerperal GAS infections is often atypical with extremes of temperature, unusual and vague pain, and pain in extremities. Toxin production by the organism may allow GAS to spread across tissue planes and cause necrosis while evading containment by the maternal immune system in the form of a discrete abscess. Endometrial aspiration in addition to blood cultures may be a useful rapid diagnostic tool. Imaging may appear normal and should not dissuade the clinician from aggressive management. When suspected, invasive GAS infections should be treated emergently with fluid resuscitation, antibiotic administration, and source control. The optimal antibiotic regimen contains penicillin and clindamycin. Source control may require extensive wound or vulvar debridement, hysterectomy, or a combination of these, which may be life-saving. The benefit of immunoglobulins in management of puerperal GAS infections is unclear.