The role of cardiac oestrogen receptor expression and local oestrogen synthesis in the pathogenesis of cardiovascular disease is poorly understood. Therefore we studied the effects of the oestrogen precursors androstendione and testosterone on the expression of cyp450 aromatase, oestrogen receptor alpha and beta, and inducible NO synthase (iNOS) in neonatal rat cardiac myocytes. Here, we show that cyp450 aromatase is expressed in cardiac myocytes and incubation of cardiac myocytes with oestrogen precursors leads to sexual dimorphic transactivation of an oestrogen-responsive reporter plasmid. Furthermore, incubation with oestrogen precursors stimulated expression of oestrogen receptor alpha and beta, and iNOS in a gender-specific fashion. These data suggest that local oestrogen biosynthesis of the heart is effective to activate oestrogen receptor alpha and beta, and downstream target genes in a gender-based fashion and may therefore contribute to the beneficial effects of oestrogen in the pathogenesis of cardiovascular disease.