Touch preparation cytology of breast lumpectomy margins with histologic correlation. Residual microscopic disease after lumpectomy for breast cancer may cause significant local recurrence. We evaluated one hundred fourteen consecutive breast lumpectomy margins in this study by touch preparation cytology. Cytologic preparations were intraoperatively correlated with gross and frozen section results and subsequently with permanent histologic sections of representative margins. Three specimens were cytologically unsatisfactory and 86 yielded benign findings, while material suggestive or diagnostic of malignancy was obtained from 25 specimens. Gross, frozen section, and permanent histologic margins were positive in 10, 17, and 22 cases, respectively. There were three false-positive touch preparation cytologic results, while frozen section specimens were false-negative in five cases. Sensitivity and specificity of touch preparation cytology were 100% and 96.6%, respectively, with a diagnostic accuracy of 97.3%. Touch preparation cytologic examination rapidly and reliably evaluates lumpectomy margins and overcomes sampling errors and artifacts related to frozen section evaluation. This technique currently complements frozen section evaluation of lumpectomy margins as part of a protocol aimed at reducing local recurrence of breast cancer. 