The study evaluates whether child abuse professionals (CAP) incorporate medical information into abuse estimates in concordance with Bayes' Theorem. Eighty-nine CAP estimated the abuse probability for a hypothetical preadolescent female: (1) randomly selected; (2) disclosing abuse; (3) with physical evidence of abuse; and (4) disclosing abuse but with a normal physical examination. The non-medical professionals varied considerably in their estimates of the baseline probability of abuse. The respondents managed the uncertainty inherent in the physical examination for sexual abuse in a Bayesian manner, although they discounted the value of medical information more than was warranted according to Bayes' Theorem. Results suggest that decisionmaking by non-medical CAP might be improved if they could be taught a reasonable, consistent estimate of the baseline probability of abuse and a decisionmaking strategy for adjusting this estimate based on new information. Tables, bibliography