We describe a simple method for displaying and evaluating the concordance or discordance between cytotechnologists (CTs) and cytopathologists (CPs) on gynecologic cases. The provisional diagnoses made by the CTs and the final diagnoses of the CPs are captured by the laboratory information system; data generated for specified periods are displayed as a 10 x 10 matrix that classifies each possible diagnosis made by the CT and CP into 1 of 10 major categories. Matrices are generated for the entire laboratory and for individual CTs; individual CTs are evaluated based on their deviation from the laboratory average. Three statistical measures are generated: percentage of discordant diagnoses, a kappa statistic, and a weighted measure. During a 2.5-year period, approximately 4,200 cases were referred to a CP for review every 6 months. The median discordance in diagnoses increased during 2 years from 21% to 34%, and the kappa value fell from 0.69 to 0.38. This was attributed primarily to 1 CT, whose performance, as well as that of the entire laboratory, improved after remedial action. Measures of CT-CP diagnostic concordance are a useful and efficient measure of CT performance and can be incorporated into mandatory semiannual performance evaluations.