OBJECTIVES: The purpose of the study was to explore foreign medical graduates' (FMGs) performance on a clinical skills (SPX) examination. The National Board of Medical Examiners (NBME) is in the process of developing an SPX for potential use in the United States Medical Licensing Examination (USMLE). The Educational Commission for Foreign Medical Graduates (ECFMG) is developing the Clinical Skills Assessment (CSA) as an additional requirement for FMGs who wish to be certified by ECFMG. DESIGN: Thirty-three FMGs and 151 United States medical students (USMSs) took the SPX during the winter of 1996 as part of the ongoing pilot studies conducted by the NBME. Four clinical skill areas were assessed: history-taking, physical examination, communication and interpersonal skills. The examination used in this research consisted of 12 cases. The examination utilizes standardized patients (SPs) who are trained to document examinee behaviours and evaluate the communication component of the test. The SPs were also trained to evaluate the English proficiency of the candidates. Candidates were also administered the Test of Spoken English developed by the Educational Testing Services (ETS). SETTING: The examination was conducted in one medical school which served as an SPX centre for NBME pilot studies. SUBJECTS: Thirty-three foreign medical students and 151 US medical students. RESULTS: The indications were that the majority of candidates in both groups felt the examination was moderately fair but 78% of FMGs felt moderately pressed for time, vs. 80% of the USMSs who did not feel pressed for time. Reliabilities obtained for the various SPX components were somewhat higher for the FMGs reflecting the heterogeneity of this group. CONCLUSIONS: The NBME-ECFMG collaborative study yielded important information regarding the NBME SPX prototype as a performance measure for FMGs.