Cytological smear techniques have been found valuable in obtaining a rapid histological diagnosis during neurosurgical biopsies, although their accuracy is questioned. This method is particularly appropriate in the case of small pieces of tissue which may be difficult to cut in the cryostat. A method developed to obtain multiple touch preparations was used in 332 consecutive neurosurgical biopsies; these were examined and compared with subsequent paraffin sections of the same biopsies. The correct diagnosis was obtained from the smears in 93.7% of the cases, while the diagnostic accuracy of paraffin sections was 98.2%. The imprints also allowed correct grading of gliomas. Most of the errors or inconclusive cytological diagnoses stemmed from failure to distinguish between primary and secondary anaplastic CNS tumours, between neurinomas and fibroplastic meningiomas, or between glial scar or normal brain tissue and isomorphic astrocytomas. The differentiation of these lesions is, however, often difficult even in paraffin sections. In accordance with the results of other authors it is suggested that the touch cytology is one of the most appropriate techniques available for rapid neurosurgical diagnosis.