Introduction: Multiple Sclerosis has been described as a chronic inflammatory disease of the central nervous system with progressive demyelination of nerve cells and damage in sensory-motor pathways that cause specific neurological and psychological symptoms3. 95% of these patients experience neurophysicatric symptoms1. Here is a case of untreated Multiple Sclerosis presenting as psychosis. Case Description: We have a case involving a 37-year-old African American male admitted due to bizarre behavior. On examination, the patient appeared disheveled, guarded, and was minimally cooperative with the interview. He exhibited thought blocking, scanning sight, and appeared to be responding to internal stimuli. On physical examination, bilateral upper extremity tremor was noted as well as gait instability. Per collateral information disclosed that the patient had been diagnosed with Multiple Sclerosis in 2019 but never received any treatment. Imaging including a Brain CT and MRI were conducted. The findings were consistent with those of MS: periventricular, subcortical, cerebellar, and brainstem lesions. Neurology team was consulted for further assessment which identified spastic paraplegia, dysmetria, and dysdiadochokinesia. He was diagnosed as having primary progressive multiple sclerosis, complicating psychiatric illness. He was treated with risperidone 1mg PO twice daily with complete resolution of his symptoms of psychosis. Discussion: Multiple Sclerosis psychosis treatment is well known2. Antipsychotics, such as Risperidone, are the treatment for such cases 3,4,5. This case highlights the importance of a comprehensive evaluation of psychiatric patients. It also demonstrates the importance of a proper history which should include an account from, not only the patient, but collateral participants.