Summary: Skin scrapings, mouth swabs, and faecal specimens from children with eruptions in the napkin area and from a series of normal infants were examined for the presence of Candida albicans.This was found in 41% of all napkin eruptions but in only one of the 68 normal infants. While C. albicans is a common secondary invader of all types of napkin eruption, primary candida infection of the skin in the napkin area is probably uncommon.No evidence was found that generalized psoriasiform or eczematous eruptions occurring in association with napkin rashes are due t an allergic response to the fungus. C. albicans is more likely to be present in a napkin rash if the organism has been found in the alimentary tract. IntroductionFour main types of napkin eruption are usually described, and include the common napkin rash due mainly to irritation by ammonia, seborrhoeic (intertriginous) eczema, a psoriasislike eruption (napkin psoriasis), and an eruption reported as a primary Candida albicans infection. C. albicans is well recognized as an opportunist organism growing where general and local conditions are favourable, and among these conditions moisture and a pre-existing skin disorder are important. C. albicans has been recovered from the alimentary tract of up to 31 % of infants under the age of 9 months (Beare, Cheeseman, and Mackenzie, 1968), and it is therefore not surprising that the organism has been isolated from napkin rashes of all types. When so discovered C. albicans may well be accepted as having a primary role in the napkin eruption, and psoriasiform or eczematous lesions which may develop in other sites of the body have often been considered to be either a spread of the infection or an allergic response to the fungus.In the present investigation we compare the prevalence of C. albicans infection of the skin and alimentary tract in children with different patterns of napkin eruption and in a series of normal controls. Our purpose was to determine, firstly, whether infections of the skin in the napkin area by C. albicans were more likely to be primary or secondary in origin, and, secondly, whether there is any evidence for a causal relationship between C. albicans infection and generalized psoriasiform or eczematous eruptions. MaterialThe cases included in the investigation were either referred by their doctors to the dermatological outpatient department of one of the Bristol hospitals or were attending certain of the local authority's child welfare clinics. Very little further selection was made. All children with a napkin eruption who attended the dermatological clinic at the Royal Hospital for Sick Children during the period of the investigation were included. Occasionally in child welfare clinics time did not permit the inclusion of some children with a napkin rash, but this happened only rarely.