Chronic abuse of drugs may lead to pathological changes within the nervous system. In this article we present the neurological and Magnetic Resonance Imaging (MRI) findings in a group of seven drug abuse patients. The MRI for three of the patients showed areas of demyelination in white matter. Of the four patients with normal MRI, two showed seventh nerve paresis, one showed abnormal cerebral blood flow when measured with Positron Emission Tomography and one patient had no evidence of neurological impairment. We hypothesize that some of the neurologic and psychiatric complications of drug abuse may be due to its effects on the cerebral circulation.