Performance-based examinations that use standardiied-patient (sp) cases have been used to assess the clinical competence of senior medical students in eight classes (1986 to 1993) at southern illinois university school of medicine. Two or more (multiple) sps have been used to simulate about half the cases in each examination. This study was conducted to assess the effect of multiple sps on the intercase reliability of sp ratings of interpersonal and communication skills. In general, results showed little effect of multiple sps on reliability of ratings of interpersonal and communication skills. For example, for ratings on overall patient satisfaction, the generalizability coefficient computed without including measurement error due to multiple sps was. 78, Whereas the coefficient computed with measurement error due to multiple sps included was. 73Suggesting that use of multiple sp raters on the same case reduced reliability by about. 05. Similar results were obtained for ratings on the other dimensions. The magnitude of the effect on the reliability of ratings would not seem to present a serious psychometric concern. 1994, Taylor & francis group, llc. All rights reserved.