Background: The abnormal illness behaviours characterising somatisation disorder may be learnt responses acquired through exposure to parental illness and health anxiety in childhood. In this observational study we explore this hypothesis by examining patterns of interaction in mothers and their school age children. Method: A sample of 136 mother and child pairs in 3 groups (42 mothers with somatisation disorder, 44 organically ill mothers and 50 healthy mothers) completed a battery of self-report and interview measures. Their interaction in semi-structured play tasks and a meal was videotaped and later analysed for the presence of "needs" and "offers of care" by researchers who were blind to maternal group membership. Results: During play, a greater proportion of the children of somatising mothers expressed "health and safety" needs than did children of other mothers. In contrast, during a meal, these children expressed fewer needs of all types. Children of somatising mothers were more likely than other children to ignore their mothers' offers of care. The somatising mothers expressed more health and safety needs during the meal than did other mothers and were generally less responsive to all needs expressed by their children. Conclusions: Our study suggests that mothers with somatisation disorder and their children interact differently than other mother-child pairs. This finding supports the theory for environmental influences in the development of this disorder.