Shoot cultures of four genotypes of Populus deltoides Bartr. ex Marsh. were established from adventitious shoots regenerated from internodal stem explants. Stable shoot cultures for all four genotypes were maintained in a continuous culture regime for over one year. The stable shoot cultures were used as explants to investigate the effects of zeatin concentration and genotype on axillary shoot production and growth. The concentration of zeatin significantly affected the production of axillary shoots, with 1.0 mgL(-1) zeatin producing the greatest number of shoots (31.0 shoots per culture vessel) while 0.25 mgL(-1) zeatin produced the greatest growth (5.9 mg per axillary shoot) when measured by dry weight accumulation per shoot. Genotypic differences were significant in the production and growth of axillary shoots.