Utilization of genistein as a natural inhibitor was studied alone and in combination with conventional treatments on melanosis and microbial quality of fresh L. vannamei during 10 days ice storage. Treatments were as followed: A (dipping samples in distilled water), B (dipping in 1.25 % sodium metabisulphite solution), C (dipping in 0.01 % genistein + 2% glycerol solution), D (dipping in 0.1 % genistein + 2% glycerol solution), E (dipping in 1% NaCl + 0.05 % EDTA + 0.5 % ascorbic acid + 0.5 % lactic acid solution), F (dipping in 0.01% genistein + 2 % glycerol + 1 % NaCl + 0.05 % EDTA + 0.5 % ascorbic acid + 0.5 % lactic acid solution) and G (dipping in 0.1 % genistein + 2 % glycerol + 1 % NaCl + 0.05 % EDTA + 0.5 % ascorbic acid + 0.5 % lactic acid solution). Results showed that G treatment was more affective on inhibiting of melanosis in L. vannamei. Mesophilic and psycrophilic bacterial counts in G treatment were lower than other treatments during ice storage.