A study was carried out in Kuwait, a country with low levels of fluoride in the water supplies, to determine the prevalence and extent of caries in early childhood, and enquire into associated factors. Mothers of pre-schoolchildren were interviewed, and their children aged 18 to 48 months received a dental examination. Of the 227 children examined, 107 (47 per cent) were caries free, and 41 (18%) had five or more dmf teeth. 'Nursing caries', affecting at least two maxillary incisors, was seen in 19 per cent of the sample. Breast fed children were significantly more likely to be caries free than those who were bottle fed from birth, although 'nursing caries' was positively associated with the practice of breast feeding at night 'at will' after 6 months of age (P < 0.01). Bottle fed children were more likely to develop caries, including 'nursing caries', particularly when the practice was continued to an older age. It was concluded that 'nursing caries' constitutes a significant dental health problem in Kuwait.