More than 900 cases of scarlet fever were recorded in Hong Kong during January–July, 2011. Six cases were complicated by toxic shock syndrome, of which 2 were fatal. Pulsed-fi eld gel electrophoresis patterns suggested a multiclonal epidemic; emm12 was the predominant circulating type. We recommend genetic testing of and antimicrobial resistance monitoring for this reportable disease. Scarlet fever is caused by infection with Streptococcus pyogenes and mainly affects children. An upsurge of scarlet fever occurred in Hong Kong, People’s Republic of China, in 2011, exceeding baseline annual incidence rates for the previous 2 decades. We investigated possible changes in clinical severity, transmissibility, and characteristics of the causative pathogen for this outbreak.