A prospective study employing a randomly assigned control group was conducted to assess the usefulness of a chart audit in teaching paediatric residents the components of well child care. The charts of children less than 5 years of age were reviewed and compared with audit criteria. Per cent compliance scores were calculated for five categories: present history; behaviour-development; family history; past medical history; and physical assessment. Five separate audits (10 charts per resident per audit) were conducted--two prior to giving the residents feedback, one after informing them that a study was being conducted, once a month after giving feedback, and one a year later. There was no significant difference between the baseline scores of the two groups. In addition, there were no significant changes in the experimental group's scores during the first three audits or the control group's scores over the whole 3-year course of the study. However, one month after receiving feedback, the scores of the experimental group improved significantly in present history, behaviour-development, and past history. One year later, the experimental group's scores were lower in every category than in the preceding audit. However, their scores were higher than the control group and the difference reached statistical significance in present history. We conclude that regular chart audits with feedback are a valuable addition to the primary care curriculum in a paediatric residency programme.