Cloth diapers, cellulose core diapers (conventional disposable diapers), and cellulose core diapers containing absorbent gelling material were examined for their effects on diaper rash and skin microbiology of normal infants and infants with atopic dermatitis in a 26-week double-blind clinical trial. Infants with atopic dermatitis wearing the diapers containing absorbent gelling material had significantly lower diaper rash grades than infants with atopic dermatitis wearing cloth diapers at five of eight grading visits. Infants with atopic dermatitis wearing conventional cellulose core diapers had statistically less rash at one of eight visits. There was no statistically significant difference between diaper types at three of the eight visits. At no time did the cloth group have less diaper rash than the conventional cellulose or absorbent gelling material disposable diaper group. A statistical correlation between the severity of general atopic dermatitis outside the diaper area and the diaper rash condition under the diaper occurred only in the atopic dermatitis group wearing cloth diapers. Isolation of microorganisms from the intact, uninvolved skin surface both inside and outside the diaper showed no biologically significant changes in the presence or numbers of selected skin organisms. Repeated isolation, at multiple grading visits of Staphylococcus aureus from uncompromised skin inside the diaper area was infrequent but correlated with the diagnosis of atopic dermatitis when observed.