The American Osteopathic Board of Internal Medicine has been examining various factors that may affect candidate performance on subspecialty certifying examinations. To see whether taking subspecialty training in an osteopathic compared with an allopathic institution could predict better performance on the certifying examinations, the authors analyzed examination performance for all candidates from 1984 through 1992. There was no significant difference between the mean scores for the two groups for any of the nine subspecialty certifying examinations. When the results from all nine examinations were pooled, the mean first-time examination takers' score for candidates in allopathic subspecialty programs (n=201) was 78.3 and for those in osteopathic sub-specialty programs (n = 153), 77.4 (P>0.2). On the basis of these results, we cannot conclude that osteopathic subspecialty training is a factor that predicts better performance on the subspecialty certifying examination.