In newborn English Infants, the predominant faecal bacteria were coliforms and bacteroides, as shown by Gram film, culture, and gas-liquid chromatography, whether they were bottle fed or exclusively breast fed. This contrasted with bifidobacterial predominance in faeces from breast-fed Nigerian infants. Presumably environmental factors other than exclusive breast feeding are also important for establishing the flora. No differences were detected between the flora of infants of atopic and non-atopic controls.