Over a 17-month period 77 patients requiring a split skin graft for a burn injury have suffered loss of previously well taken graft due to the growth of a beta-haemolytic streptococcus. Of these only 42 were streptococci of Lancefield group A (Streptococcus pyogenes); 16 were group B, 3 group C and 16 group G. Some strains of groups B, C and G produce cytopathic and spreading factors capable of destroying the new skin graft and regenerating epithelium. We suggest that the non-group A streptococci may be more pathogenic than previously recognised in this particular respect.