Substantial improvements in measuring and reporting errors in gynecologic cytology have been made during the last decade. Measuring and reporting errors in surgical pathology recently has gained renewed interest. However, review of current literature demonstrates mistakes in how these data are measured and reported. Error rates have been reported from review of consecutive material, biopsy material, and consultation material and range from 0.25% to 43%. Errors have been divided into anatomic regions and specimen types and separated according to their clinical significance. However, to be comparable, errors must be reported in reference to the incidence of disease and not to overall caseload. Blinding and reviewer error have been addressed only rarely, and the true incidence of errors is almost certainly higher than reported. "Gold standards" are not well defined. In addition, available data strongly suggest that the greatest source of error is with false-negative diagnoses, which are detected only rarely by review of consultation material. Most of these issues have been addressed in the gynecologic cytology literature. Errors in surgical pathology are more common than generally believed, and efforts should be made to define methods that allow appropriate interlaboratory comparisons.