Altered immunological functions and changes in the monoaminergic neurotransmitter systems are two important observations made previously in the study of possible etiological and pathophysiological factors for psychiatric disorders. In search of tentative autoimmune mechanisms involved in these disorders we studied the presence of immunoglobulin G (DA-IgG) with affinity for the monoamine dopamine (DA) in cerebrospinal fluid (CSF) using ELISA. In CSF from 49 suicide attempters the titer of DA-IgG was significantly higher (P<0.001) than in CSF obtained from control subjects undergoing neurological investigation. The results in the present study indicate that an autoimmune mechanism may be involved in the dopaminergic neurotransmitter system and may be of pathophysiological importance in psychiatric disorders connected to an attempt of suicide.