Following a two-year cohort study of diarrhoeal diseases in children aged 0-35 months from a shanty town in Lima, 62 families were chosen for detailed observation of hygiene practices. All handwashing and defecation episodes which occurred during a 10-hour observation period (8am-6pm) were recorded. The youngest child in each family was selected as the index child for observation. Handwashing was seen on 483 occasions with 71% of the index children and 80% of mothers observed at least once. The use of clean water, soap and the thoroughness of the handwashing varied according to the purpose, with "better" behaviour observed more frequently when the person was preparing to go out. Forty-five index children (72%) were observed to defecate at least once. Infants defecated in their diapers or clothes; toddlers defecated more indiscriminately around the home area. Handwashing after defecation was rare (11% of occasions) and usually without soap. Faeces were often left accessible to children and animals (42% of occasions), especially when defecation occurred around the home/yard, and the data suggested this occurred more frequently in "higher" diarrhoea households. Stools deposited on the floor were usually just swept aside, covered with earth or eaten by dogs. Those deposited outside the home were frequently left untouched during the observation period or similarly cleared. Soiled clothes were usually left or washed separately, and stools in potties were thrown in latrines. These results suggest hygiene interventions might focus on clearance of stools from home surroundings, increased utilisation of potties and separate washing of soiled clothes.