Abstract: In higher animals, estrogen can regulate lipid metabolism of females; however, whether estrogen regulates fish lipid metabolism is unclear. To explore effects of estrogen on lipid metabolism in zebrafish, letrozole (LET) and tamoxifen (TAM) were treated female zebrafish (0.14±0.01) g for 5 weeks to measure triglyceride (TG) concentrations in liver, visceral and muscle and the expressions of the hepatic genes related to estrogen and lipid metabolism. The results showed that low dose LET significantly increased TG in liver and viscera but not in muscle. Low dose TAM did not impact No TG content in all tested tissues but high dose TAM significantly decreased liver TAG. LET and TAM significantly induced CYP19A mRNA, and low dose TAM decreased ERα. LET increased FAS but decreased MTP expression. DGAT had an increase tendency, and CPT-1 and PPARα had a decreased tendency. It suggests a dyslipi-demia symptom in the LET exposure groups. Low dose TAM reduced MTP and high dose TAM enhanced it (P < 0.05). These results showed important role of estrogen in lipid metabolism in female zebrafish with a complex dosageand tissue-dependent pattern.