In the last two decades imaging of the brain, or neuroimaging, has become an integral part of clinical and research psychiatry. This is due to recent advances in computer technology, which has made it relatively easy to generate brain images representing structure and function of the central nervous system. Currently used clinical diagnostic imaging modalities, such as X-ray computed tomography (CT) and magnetic resonance imaging (MRI) , provide predominantly anatomic information. CT images reflect X-ray attenuation distribution within the brain, whereas MRI signals depend primarily on proton sensitivity and tissue relaxivity. The chapter "Structural Imaging Methods" reviews CT and MRI studies on schizophrenic and affective disorders and degenera tive central nervous system diseases. The impact of fast three dimensional (3-0) imaging and the automatic transfer from 3-D elements in the brain to artificial diagrams based on this information is considered. Since the original report of the findings of Ingvar and Franzen in 1974 and the introduction of regional cerebral blood flow (rCBF) measurements, single photon emission computed tomography (SPECT) has been gaining acceptance as one of the major imaging techniques, and it is available in most nuclear medicine depart ments. The section "Functional Imaging Methods (Cerebral Blood Flow - CBF, Single Photon Emission Computerized Tomography - SPECT)" describes rCBF studies with the 133Xe inhalation method utilizing a 254 detector system and rCBF images measured by SPECT using the tracer 99mTc-HMPAO.