A double-blind, 28-day, placebo-controlled study was conducted with three groups of women of child-bearing age (N = 12 in each group) who received standardised antipsychotic medication plus a) 50 microg transdermal estradiol or b) 100 microg transdermal estradiol or c) transdermal placebo. Preliminary analyses show that women receiving 100 microg of estradiol made greater improvements in the symptoms of schizophrenia than either the 50 microg estradiol or placebo groups. The addition of 100 microg adjunctive transdermal oestrogen significantly enhanced treatment responsivity of acute, severe psychotic symptoms in women with schizophrenia. The positive impact of oestrogen treatment on psychotic symptoms via a multiplicity of possible actions (see accompanying articles in this issue) may prove clinically useful in the overall treatment of women with schizophrenia.