The relative weight of the free wall of the cardiac right ventricle was ascertained in 177 instances of the sudden infant death syndrome and 30 control infants who had died either in accidents (ten) or of fulminant illness (20). In contrast to the observations of Naeye et al in this regard, these victims of crib death did not exhibit right ventricular hypertrophy. Other evidence to support Naeye et al's contention that such infants are morphologically demonstrably different from normal is well documented. Hence, the significance of this discrepancy between our findings and theirs is unclear.