Optimal conditions of protoplast isolation from the seaweed Prophyra pseudolinearis have been described. The P. pseudolinearis is one of indigenous and dominant Porphyra species in the East Sea region. Protoplasts have been released by enzymatic treatment of 2% agarase and 2% hemicellulase in 25mM MES buffer, pH 6.0 containing 0.5 M sorbitol. The protoplasts could be fused with neutral red-stained protoplasts of P. okamurae by the addition of polyethylene glycol 8000 solution.