Although estrogen has effects on the heart, little is known regarding which genes in the heart are directly responsive to estrogen. We have shown previously that lipoprotein lipase (LPL) expression was increased in female hearts compared to male hearts. To test whether LPL gene expression in heart is regulated by estrogen, we perfused mouse hearts from ovariectomized females (OVX) with 100nM 17ß-etradiol or vehicle for 2 hours after which hearts were frozen and RNA was isolated. The SYBR green real-time PCR method was used to detect LPL gene expression. We found that addition of 17ß estradiol to hearts from OVX females resulted in a significant increase in LPL mRNA. This estrogen effect on LPL gene expression in mouse heart can be blocked by the estrogen receptor antagonist ICI 182,780 or by progesterone. We also identified a potential estrogen receptor element (ERE) enhancer sequence located in the first intron of the mouse LPL gene. The potential ERE sequence was linked to a TATA-LUC reporter plasmid in HeLa cells. Both estrogen receptor (ER) and ER stimulated strong activity on the heterologous promoter reporter in Hela cells upon estrogen addition. Both ER and ER activities on the LPL ERE reporter were abrogated by the estrogen receptor antagonist ICI 182,780. Progesterone also dose dependently inhibited the estrogen mediated increase in LPL ERE reporter activity. These results show that heart LPL is an estrogen responsive gene exhibiting an intronic regulatory sequence.