Evaluation of educational material has become very important in a climate where there is increasing concern with assessing and maintaining quality. DIALOG (acronym for Distance Interactive Learning in Obstetrics and Gynaecology) is an electronic program on CD-ROM for continuing education. A formative evaluation of DIALOG was carried out to determine whether DIALOG was achieving its educational objectives. The results of the evaluation helped to suggest '10 golden rules' for designing software for the purpose of CPD for medical practitioners. These 'rules' should help in designing future software in medical education. They highlight the importance of content, presentation, design, use of hypermedia and multimedia and reduced cost in order to facilitate appropriate use of such programmes.