Abstract: Expression patterns of IGF-ⅠmRNA in different tissues of mud carp (Cirrhinus molitorella)were studied using semi-quantitative RT-PCR method and the effects of recombinant mud carp growth hormone(rmcGH)on expression of IGF-Ⅰin mud carp were investigated. The IGF-ⅠmRNA was detected successfully in liver, kidney, brain, intestine, gill, spleen, gonad, and heart, and no IGF-ⅠmRNA was detected in skin and muscle. The IGF-Ⅰ mRNA detected was higher in liver than in other tissues. Mud carp were received either intra-peritoneal injections of rmcGH (120 μg·g^-1 body weight) or vehicle, tissue samples and blood were collected 12 hour later. Total RNA was isolated and assayed for IGF-ⅠmRNA using semi-quantitative RT-PCR. Blood was extracted to determine the levels of IGF-Ⅰ in serum. IGF-Ⅰlevels increased from 145.59±21.84 to 247.71±2.83 ng·mL^-1 (P=0.043) in the serum after rmcGH injection.