Naphtenic acids, by-product in oil refinement, are well known soil pollutants and active substances in preparations for plant and wood protection. The results of multiannual research indicated the possibility of their utilization for stimulation of cutting rooting. Two to three cm high shoots of Populus alba cl. LBM genotype were set for one hour on ACM medium with 4, 16 or 48 μM concentration of indol-3-butyric acid, 1-naphthalene acetic acid or Na-salts of naphthenic acids (for which the effect of 10 and 30 minutes treatment on medium with 48 μM was also examined). Then, treated microshoots were transferred on ACM medium without hormones. The differences among treatments were the most distinguishable for rooting percentage after two weeks of cultivation. One-hour treatment on the medium with 16 μM and 30 minutes treatment on medium with 48 μM of Na-naphthenates gave the best results.