Callogenesis was induced in mature embryos. The efficiency of induction and the growth of calli were dependent on 2,4-D concentration. No regeneration of buds or shoots was observed in 720 calli studied, but most calli showed intensive root proliferation on the regeneration medium. Most of the root meristem cells maintained diploid chromosome number. Only a low proportion (about 3.5%) of tetraploid cells was found. No other chromosomal changes were observed. Chromosomal variability does not contribute to the inability of calli derived from mature barley embryos to form buds and shoots.