The range of neuropsychiatric symptoms in multiple sclerosis (MS) has not been prospectively assessed. The authors, working at a tertiary medical center in Mexico City, used the Neuropsychiatric Inventory (NPI) to evaluate neuropsychiatric symptoms prospectively in 44 MS patients who were stable between relapses and 25 control subjects of similar age, education, and cognitive function. Neuropsychiatric symptoms were present in 95% of patients and 16% of control subjects. Changes present were depressive symptoms (79%), agitation (40%), anxiety (37%), irritability (35%), apathy (20%), euphoria (13%), disinhibition (13%), hallucinations (10%), aberrant motor behavior (9%), and delusions (7%). The only relationships with MRI were between euphoria and hallucinations and moderately severe MRI abnormalities. The authors conclude that diverse types of neuropsychiatric symptoms are common in MS; symptoms are present between exacerbations; and there are variable correlations with MRI abnormalities.