Somatic hybrid plants were obtained by protoplast fusion in the Rutaceae family. Protoplasts isolated from nucellar calli and from leaves of nucellar seedlings were fused by the PEG method. The fusion products were cultured in a Murashige and Tucker medium containing 0.6 M sucrose. In this medium, some colonies developed into the whole plants through embryogenesis. Almost all of the plants were shown to be somatic hybrid, which were proven by the restriction endonuclease analysis of nuclear ribosomal DNA. The chromosome number of the hybrid plants was 36, which was the sum of the parents (2n=18).