Initial experience using the Fischer ZD-Neurosurgical Localizing Unit is reviewed. During the first year, 26 stereotactic procedures were performed in 25 patients. Twenty-two patients underwent imaging-guided stereotactic biopsy. Among them, 20 were included in the protocol we have developed for combined positron emission tomography (PET)- and computerized tomography (CT)-guided stereotactic biopsy. The technique is briefly described and preliminary results are reported. Most low-grade tumors were found in hypometabolic/hypodense areas, glioblastomas were all diagnosed in areas with increased FDG uptake and contrast enhancement on CT while data for anaplastic astrocytomas were heterogeneous. Some of the biopsic trajectories performed in areas were there was no increased FDG uptake or in areas with increased FDG uptake but without contrast enhancement on CT were non diagnostic. This never occurred in areas with both increased FDG uptake and contrast enhancement. Other stereotactic procedures performed include 2 catheter placement for drainage of cystic lesions, 3 stereotactically guided open neurosurgical procedures and 1 third ventriculostomy. Procedural objectives were accomplished in all cases. From our experience, we found stereotactic procedures using this system safe, accurate, easy to handle and allowing a wide range of applications. Because the system is designed to be readily used in conjunction with modern planar imaging techniques (i.e. CT and magnetic resonance imaging), it allowed us to develop a technique for PET-guided biopsy which might increase the diagnostic yield of stereotactic biopsy of intracranial neoplasms.