This article describes a 1-year study undertaken to evaluate the cost and effectiveness of a surgical pathology quality assurance system in which a second pathologist routinely reviews (before release of the report) all surgical pathology cases requiring microscopic sections. The study included 5,397 cases. Fourteen discrepancies of potential clinical significance were detected by the second observer, for an error rate of 0.26%. Consultation with the clinical physicians involved in these cases indicated that in seven of these cases, the error would have resulted in a different clinical intervention than actually occurred. This "checker" sign-out system added an estimated $7 to the cost of each case, or $2,700 for each discrepancy of potential clinical significance. The value of the dual pathologist sign-out system as described here requires confirmation, because there is a paucity of information in the literature relating to routine surgical pathology sign-out accuracy.