Elimination of medical errors is important for pathologists. Errors occurring in surgical pathology involve specimen defects, specimen labeling, processing, diagnosis, and reporting defects. Errors occur during prelaboratory, laboratory, and postlaboratory phases. We reviewed our experience with mislabeled specimens in the laboratory for an 18-month period. The percentage of error was calculated on a per case, block, and slide basis. Errors were characterized by site and as incorrect patient or site. The study involved 75 labeling errors (0.25% of cases) that were detected. Of the 75 errors, 55 (73%) involved patient name, and 18 (24%) involved site. The majority of mislabelings (52 [69%]) occurred in the gross room. Although infrequent, labeling errors involved misidentification of patient or specimen source. Of the errors, 73% (55/75) of errors resulted in slides assigned to an incorrect patient. Most errors occurred in the gross room. Newer technologies such as bar coding and radio frequency chip methods may reduce the frequency of specimen labeling errors.