The resident in-service examination in pathology is an in-training exercise that is taken by virtually all pathology residents in the United States as well as by some participants in Canada, Ireland, and Lebanon. Although all of the anatomic pathology topics in the examination, with only one exception-forensic pathology, show significant improvement in scores over the 4 years of residency training, three areas of clinical pathology training (laboratory administration, clinical chemistry, and microbiology) show significantly lower improvement in performance over the years of residency training. By contrast, transfusion medicine, hematopathology and the special topics section of the examination all demonstrate improved performance by residents over time. While the reason behind these differences must remain speculative at this time, these findings suggest that measures to improve effectiveness in clinical pathology training might be suggested by examining the differences between residency training practices between higher and lower performing areas of clinical pathology.