Data concerning histories of Adenoidectomy (Ad), Tonsillectomy (T) and Appendectomy (Ap) were collected from the escorts (mainly mothers) of 2296 children 3-12 years-old. The children were admitted as outpatients at the First Department of Paediatrics of the University of Athens or the Polyclinic of the Children's Welfare Center of PIKPA in Pireaus, during the last six months of 1983. Among children with median age of about six years, 12 percent had already had at least one operation (Ad, T or Ap); this proportion increased to about 25 percent among children with median age of about 10 years. The cumulative incidence of Ad and/or T was higher among boys, whereas the cumulative incidence of Ap was higher among girls. The age adjusted cumulative incidence of Ap was significantly higher in the lower social class, whereas there was no social gradient with respect to Ad or T. There were strong intra-individual correlations among the three studied operations; in particular the age adjusted cumulative incidence of Ap was 2.9 times higher among children with Ad and/or T than among children without any of these operations. Since there are no apparent biomedical reasons to account for the observed intra-individual associations, it appears likely, that these associations reflect parental or physician's attitudes leading to unjustifiable operations in some of the children.