In a combined anthropological and parasitological study in a rural Balinese village, two distinct sub-populations were identified on the basis of nutritional and health practices. A significant negative correlation between Ascaris burden and nutritional status (P less than 0.05) was apparent only in the subpopulation characterized by lower nutritional intakes and low utilization of health care facilities. The results of this study suggest that the relationship between Ascariasis and child malnutritional is a conditional one, dependent upon the interaction of multiple biomedical and behavioural factors.