Continuing medical education has been widely criticized as ineffective; most such criticism is directed at the assumption that the mere transmission of information on new research findings is sufficient to change physician performance. Eight studies published during the 1970s report changes in physician behaviour (and, in one, improved patient outcomes) as a result of CME organized on sound educational principles, including systematic effort to evaluate program effectiveness and learner achievement. It is also suggested that additional information on CME effectiveness is likely to be obscured by the form in which much medical literature is presented.