Abstract: In this paper,we observed the growth enhancement of crucian carp which were treated in the following two ways:1) The fertilized eggs of the fish were microinjected with the pMhGH recombinant DNA containing human growth hormone(hGH) gene capped with mouse metallothionein-1 (MT-1) gene promoter and control sequences.Each egg received 108 copies of the novel gene.The gene transferred eggs were allowed to proceed in individual development. 2) The juvenile fish (60 days old) from part of the control group were intraperiodicly injec- ted with biosynthetic human growth hormone at the concentration of 10μg/g(bw)/week for six weeks. At the 60 and 120 days,the average body weights of the gene transferred fish were 82% and 17% heavier than those of the control,respectively.After one month of ending the hGH administration,the average body weight of the hGH injected fish (10μg/g(bw)/week) were 32.8% heavier than that of the control.On the other hand,the fish injected with 2μg/g(bw)/ week of the hGH did not show any growth improvement.