Ghrelin precursor cDNA was identified from the stomach of Zanzibar tilapia,Oreochromis hornorum by RT-PCR.The total sequence of ghrelin was 833 bp in length,consisting of 97 bp of 5′-untranslated region（UTR）,412 bp of 3′-UTR and 324 bp open reading frame （ORF）encoding 107- amino-acids prepro-ghrelin.The nucleotide sequence identities among Zanzibar tilapia and other tilapia are above 99.0%.The expression of ghrelin genes in stomach,muscle and pituitary and some other tissues in male and female Zanzibar tilapia were detected by RT-PCR.The results showed that ghrelin was widely distributed in Zanzibar tilapia tissues.High expression levels were detected in stomaches of both female and male individuals,but there were different expression levels in other tissues detected between females and males.The expression level of ghrelin in female muscle was 132 times higher than in male’s.The effect of fast on ghrelin expression in Zanzibar tilapia was also investigated using relative RT-PCR.The results indicated that the expression level of ghrelin in stomach increased in the fasting individual much more than in the normal feeding individual.The highest ghrelin expression level in fasting individual was 47.3 times than the lowest in normal ones.