Three types of clinical studies were carried out to better understand diaper dermatitis in a general infant population. In 'snapshot' clinical studies, skin condition under the diaper was evaluated at a given point in time across a large base of infants. Correlations were sought between diaper dermatitis incidence and severity and a number of factors, including sex, diet, maturity, type of diaper, history of allergy, contact with fecal matter, presence of Candida albicans, and diaper change frequency. Severe diaper rash correlated strongly with the presence of C. albicans, and the frequency of rash correlated with duration of contact with feces and inversely with diaper change frequency. Diaper rash peaked at ages 9-12 months and was lower for breast-fed than for formula-fed infants. Exclusive use of disposable diapers correlated with lower rash levels than when some or all cloth diapers were used. In a longitudinal study, infants were observed daily for 50 days in order to determine the frequency and duration of rash episodes. In this study, the tendency for some infants to be rash-prone was clearly indicated. In a third type of study, over 10,000 infant visits to physicians' offices were used to record skin condition. Results showed a three-to fourfold increase in diaper rash if the child had diarrhea during the previous 48 h.