From 1973 to 1976, 21 patients with staphylococcal toxic epidermal necrolysis were admitted to the Jikei University Hospital in Tokyo. Of all of them were isolated coagulase-positive Staphylococcus aureus from various sites. In Japan, unlike in Europe and America, phage group II cocci were found in few cases. On the other hand, S. aureus belonging to other phage groups than group II (I, III mixed group and III group) were very commonly isolated. All the isolates produced exfoliatin which was capable of producing exfoliation in newborn mice. The type (A or B) of exfoliatin which was detected by the antiserum agar method did not correlate to the severity of this disease.