AIMS--To assess the efficacy of cytodiagnosis in necropsy practice. METHODS--Fifty three focal lesions from 46 necropsies were assessed by direct smears taken from the lesions. The smears were air-dried and stained by a modified Giemsa technique, with two cases having supplementary histochemistry. All of the slides were assessed independently before review of the necropsy histology. RESULTS--Of the 35 malignant neoplasms, 34 were correctly identified as malignant and 14 of these were characterised precisely. Three of the four benign neoplasms were recognised as neoplastic. One was characterised precisely. Three of the four infected cases revealed the relevant microorganisms. Seven of the other 10 focal non-neoplastic lesions were correctly diagnosed as non-neoplastic. Only two cases proved unsatisfactory for cytodiagnosis. CONCLUSIONS--Direct smear cytodiagnosis is quick, cheap and technically simple. Tissue autolysis may account for some difficulty in assessing particular tissues, but this should diminish with experience. Necropsy cytodiagnosis is applicable to all necropsies in all centres.