Chromosome numbers were was studied in ginseng cell line 1c transformed with Agrobacterium rhizogenes strain A4, which carried plasmid pRiA4, and with A. tumefaciens strain GV3101, which carried vector pPCV002-35S rolC. As compared with the nontransformed cell line 1c, tumor cell cultures 1c-A4 and 1c-rolC and the tissues of rolC teratoma (excluding leaves) displayed higher polyploidy and aneuploidy. The 1c-A4 and 1c-rolC hairy-root cultures also had aneuploid and polyploid cells, but the chromosome variation was lower than in tumor cells or the initial culture 1c. Generally, an increase of chromosome variation in cultivated cells was the main effect of the integration of several oncogenes, which were in the A. rhizogenes A4 T-DNA, or of the individual rolC gene in the ginseng genome. Another effect consisted in stabilization of the chromosome number in some differentiated transgenic tissues. Possible reasons for this effect are discussed.