A series of 910 frozen section examination of skin lesions is presented, and the results are analysed in detail and compared with others in the literature. The difficulties in histological diagnosis are discussed and contrasted with those of clinical diagnosis especially of pigmented lesions.SummaryIn 910 consecutive frozen section examinations of skin lesions nine false positive reports were submitted, but only two were of major importance. False negative reports occurred with malignant melanomas when the lesion was small or heavily pigmented, and with other malignant lesions when the specimens were large (sampling error). Frozen section examination accurately identifies lesions that tend to be mistaken for malignant melanoma on clinical examination.