S-Adenosylmethionine blood levels have been estimated by a specific radioenzymatic method in 52 schizophrenics and 12 depressives, diagnosed and subtyped according to ICD-9 and compared with 38 normal controls. Previous reports of significantly lower levels of blood SAMe in acute schizophrenics in comparison with normal subjects could not be confirmed in this study. Indeed, acute schizophrenics showed higher mean SAMe blood levels as compared both with chronic and with normal controls. No significant difference has been found comparing both schizophrenics as a whole and depressives with normal controls. This investigation aims to bring a contribution to the recently started critical revision of transmethylation hypothesis of schizophrenia.