Sudden infant death syndrome (SIDS) remains the leading cause of death in the Western world among infants between the ages of 1 month to 1 year. The diagnosis can only be established at autopsy, at which time no obvious or recognizable pathology is evident. A correlation between thickening of the basement membrane of the true vocal cords and the victim’s age was observed in all 51 larynges examined, whereas no such finding was detected in 82 larynges of infants who died of other causes. Thus, the data support the authors’ previous morphological results suggesting the use of basement membrane thickening as a marker of positive diagnosis of SIDS at autopsy. The possibility that an immune process may be associated with this syndrome merits further investigation and could prove to be of great importance.