In this study, quantitative real-time PCR was used to compare the mRNA expression of GH, GHR, and IGF-1 genes in livers of sex-linked dwarf chickens with their normal siblings. The results showed that there was no significant difference between dwarf and normal chickens in GH expression. The expression of GHR gene was more than 3-fold higher in dwarf chickens, compared with that of the normal. However, the transcription level of IGF-1 decreased dramatically in the sex-linked dwarf. These observations suggest that the dwarf phenotype occurs independent of GH action, but is due to a dysfunctional GHR. A 1.7 kb deletion has been reported in exon 10 and the 3'untranslated region (UTR) of the GHR gene in dwarf chickens. This transcript could be translated into a protein that does not retain its normal function, which would ac-count for the absence of GH-binding activity in liver membranes of the dwarf chickens.