Over the past ten years the Italian National Research Council (C.N.R.) has carried out an educational program based on the preparation and dissemination of guidelines to facilitate delivery in community hospitals of the most up-to-date care to patients with ovarian cancer. In 1988 an assessment was begun to determine (a) whether the guidelines reached the target physician population; (b) whether they were accepted by those they reached, and (c) whether treatment patterns thereafter conformed to the guidelines. Overall results of this evaluation provide no evidence of clinically relevant effects of the program. The guidelines were not widely disseminated: only 44% of responders were aware of them. Moreover, analysis of practice patterns showed serious deficiencies in diagnostic procedure and surgical staging (information on grading and residual tumour was available only in 30% and 45% of cases, respectively, and only 10% of the patients had random biopsies as part of their surgical staging). The only observation supporting some effect of this educational intervention in terms of knowledge modification was of certain therapeutic preferences among those aware of the guidelines. This finding, however, is highly susceptible to confounding by other factors (e.g. physicians' greater expertise, spillover effect of the program) not entirely avoidable in an observational study. We conclude that any assessment of procedures based on dissemination of information must include a careful analysis of the method of dissemination. The availability of clinically applicable information must also be realistically appraised before the guidelines approach can be accepted as the most effective.