Neuropathology is a relatively scarce resource with uneven geographical distribution, and some surgeons rely on macroscopic appearances of tissue and await later paraffin section histology for the final diagnosis. The effect of the introduction of a peroperative cytology service has been assessed in a 5-year series of CT-directed stereotaxic biopsies of intracranial mass lesions using a low cost adapted pre-CT stereotaxic frame. The technique has been mastered by 28 different surgeons with varying degrees of neurosurgical expertise and 259 procedures have been performed in 245 patients. Benign lesions were detected in 24 (9.8%) patients, confirming the importance of making a histological diagnosis prior to initiating treatment. Permanent morbidity was 6.5% and mortality 3.3% and morbidity was balanced by an improvement in 19.6% of the patients following the procedure. For the first 142 patients no peroperative histological diagnosis was available and a diagnostic rate of 86.6% was achieved. For the last 103 patients the availability of peroperative smears improved the diagnostic rate to 94.2% and reduced the number of second biopsies needed for diagnosis from seven to zero. Our series demonstrates the need for peroperative cytology in CT stereotaxic biopsies, and confirms that a complete neuropathology service is a prerequisite for neurosurgical patient care.