An epidemic of 110 sudden sniffing deaths without plastic bag suffocation which occurred in American youths during the 1960's, appears to have originated on the West Coast. The incidence rate showed a sharp rise during the late 1960's. Volatile hydrocarbons most frequently involved were trichloroethane and fluorinated refrigerants. Sudden sniffing death occurred in all socioeconomic groups, with a preponderance in the suburban middle-income white family. Severe cardiac arrhythmia, resulting from light plane anesthesia, and intensified by hypercapnia or stress or activity or a combination of these, is the most likely explanation for sniffing death.