Beside well known utilization of black locust (Robinia pseudoacacia L.) in biomass production and bee-keeping, there are numerous Robinia species and genotypes of ornamental value. They are of particular interest to be propagated by means of tissue culture, where the shoot rooting is a significant phase. Results of the research of the influences of 2,3,5-triiodobenzoic acid (TIBA), well known inhibitor of indolacetic acid (IAA) polar transport and silver ions (Ag+), known to suppress the activity of ethylene were examined in this work. Two genotypes were examined: Robinia pseudoacacia L. cl. RP, the genotype of good rooting ability on medium without gorwth regulators in vitro and R. pseudoacacia x R. luxurians cl. Rózsaszín AC, whose rooting is poor on such a medium. Results gained after six weeks of cultivation suggest the significant effect of the concentration of TIBA on number of roots and significant effect of the interaction genotype x c(TIBA) on number of roots and percentage of rooted shoots. The presence of silver ions effected significantly number of roots per shoot through the interaction genotype x c(Ag+). The signifficance of gained results for further work on rooting Robinia shoots in vitro was disccused.