Protoplasts of Avena sativa L. (A) irradiated with ultraviolet light (UV) at an intensity of 300 mW/cm2 for 0 (symmetric fusion), 30s, 1in, 2min, 3min, 5min, respectively were fused by the PEG method with protoplasts of two cultivars of wheat (cv. Jinan 177 or cv. Hesheng 3). Two different sources of material were used for isolation of protoplasts of Jinan 177. Type one (T1) originated from long-term subcultured suspensions which could not be regenerated to plants, while the other (T2) derived from embryogenic calli was capable of regeneration. Protoplasts of cv. Hesheng 3 (T3) also originated from embryogenic calli possessing high regeneration capacity. Regenerated clones were produced in all fusion combinations, but only those from combinations IB and IC (irradiating A. sativa for 1 and 2min) differentiated to albinos. The clones were recognized as somatic hybrids in nature by cytological, isozyme, RAPD and 5S rDNA spacer sequence analysis. Genomic in situ hybridization (GISH) of somatic hybrid clones at mitosis always revealed the presence of recombined and intact A. sativa chromosomes in the cells. The number of intact chromosomes of donor A. sativa decreased, while the chromosome fragments translocated or inserted to wheat chromosome increased as the dosage of UV enhanced.