Recent evidence shows that NGF plays a role in the response to psychic stress in the human species and is involved in the process of apoptosis during neurodevelopment.Aim of the study was to research a possible difference of baseline NGF plasma levels between schizophrenic patients (both on neuroleptic therapy and in wash-out) and healthy controls. We studied a sample of 27 male inpatients, meeting DSM III-R criteria for schizophrenia, 21 in treatment wash-out since at last 7 days (age = 18-42; mean = 29.71; SD = 5.97) and 6 on haloperidol (6 mg p.d.) treatment (age = 17-36; mean = 25.17; SD = 8.03), compared with 29 sex and age matched volunteer healthy controls. All patients gave their informed consent. Psychopatology was assessed by means of PANSS and HAM-D. Blood sampling was effected at -10 and 0 min (baseline). NGF levels were measured using a two-site immunoenzymatic assay (ELISA). The data were analyzed using the Kruskal-Wallis test, 1-way ANOVA.Mean NGF plasma levels were significantly lower in treated schizophrenic patients (mean = 9.87; SD = 9.79) compared with patients in wash-out (mean - 18.80; SD = 11.16) and with healthy controls (mean = 32.70; SD = 17.03). The Kruskal-Wallis test showed that the subjects concern at three different groups (t = 14.76; edf = 2; p = .0006).The authors hypothesize that early NGF deficit in specific brain areas may play a role in the neurodevelopmental abnormalities linked to the pathogenesis of adult schizophrenia. These findings are consistent with recent observation in animal models of a haloperidol-induced NGF decrease of NGF in hipotalamus and bloodstream.