This study was a preliminary open clinical trial aimed at exploring the hypothesis that estrogen may provide protection against schizophrenia in women. Eleven women with acute psychotic symptoms, as scored on the BPRS, SAPS and SANS, had 0.02 mg estradiol added to neuroleptic treatment for eight weeks. Their response was compared to seven women with similar symptom severity receiving neuroleptic treatment alone. Both groups had baseline hormonal assays of estrogen, progesterone, LH and FSH and underwent regular psychopathology ratings during the eight weeks. The group receiving the estradiol adjunct showed more rapid improvement in psychotic symptoms compared with the group receiving neuroleptics only. This difference was not sustained for the entirety of the trial. Both groups reached similar levels of recovery by the eighth week. These results suggest that estradiol may have antipsychotic properties and/or act as a catalyst for neuroleptic responsiveness in women with schizophrenia.