In order to identify polymorphisms in the Tyrosinase gene for Golden rainbow trout (Oncorhynchus mykiss), a total of 100 different samples (fry) were prepared and DNA extraction was performed from their caudal fins. The polymerase chain reaction (PCR) was amplified fragment of 423bp the Tyrosinase gene. The amplified fragments were using specific primers (Tyr1.2r and Tyr1.2f) and Hinf1 cutting enzyme. In enzymatic digestion of the PCR products was observed three restricted patterns in 222bp and 201bp with NN (26 samples), and 423bp with MM (36 samples). The number of alleles N and M were 90 and 110 respectively, the gene frequency for allele N and M were .45 and .55 respectively. The number of genotypic frequencies NN, MN and MM were .26, .38 and .36 respectively. The results showed that deviations from Hardy -Weinberg equilibrium were in all cases, due to artificial reproduction, probably.