The chromosomal stability of a number of somatic hybrids derived from soybean (Glycine max (L.) Merr.) and Nicotiana tabacum var. 'Xanthi' were investigated. Several of the hybrid cell lines retained more than half the complement of N. tabacum chromosomes after 7 months of culturing. A number of chromosomal abnormalities were observed. The hybrids were positively identified by employing isozyme analysis of several dehydrogenases and aspartate aminotransferase.