Abstract: Somatic protoplast fusion has turned out to be a suitable method to overcome barriers of sexual hybridization. The actual method for successful somatic hybridization between different species of poplar such as Populus euphratica Oliv., P.cathayana Rold., P.deltoides × P.simonii NL 80106, P.euramericana cv. I 69 and P. tomentosa and different isolation materials were selected and treated with IOA and X ray irradiation to suppress division of the unfused protoplasts. Preliminary studies were performed to determine the dose of X ray irradiation to be used during fusion experiments. The optimal condition applied for fusion of the cells was also studied. One week after protoplast fusion the first division could be observed and after one month the calli 1mm long were formed. Mass of the calli derived from the fused cells between Populus deltoides × P. simonii NL 80106 and P. euphratica Oliv., P.cathayana Rold. and P.euphratica Oliv. , P.deltoides × P.simonii NL 80106 and P.cathayana Rold. were obtained, the former two of which could grow on the medium added with 0.4% NaCl. It indicated that the calli had salt resistant character of P.euphratica Oliv. which is one of the fusion partners.