A model explaining children's knowledge about medicines and the perceived benefit of medicines was constructed and estimated. The children's health belief model, cognitive development and social cognitive development theories, combined with previous multimethod study results form the basis of the path analytic model analyzed. Children, aged 7 and 10 years, and their primary caregivers were interviewed during 1992 and 1993. Recruiting was done at summer camps in Chapel Hill, North Carolina and environs, resulting in a convenience sample of 101 children, all white and middle class. Ordinary least squares regression was carried out in steps for the two model equations. Knowledge of medicines was most adequately explained, having age, educational environment and the degree of internal locus of control as significant positive predictors. The only significant predictor of the perceived benefit of medicines was the negative effect of the internal locus of control, supporting results from former studies. Children's retention of drug advertising had no significant effects in the model. The results from this moderately sized study suggest promising directions for further development of explanations of why children believe in the benefit of medicines.