Japanese plum trees of the cultivars 'Kometa', 'Najdiena', 'Skoroplodnaja' and 'Shiro' grafted on Wangenheim Prune seedlings, were planted in the spring of 2006 at the Fruit Experimental Station in Samotwor near Wroc law, Poland. As the control, trees of the 'Amers' cultivar, which belong to European plums, were used. All trees were planted at a spacing of 4.0 x 2.0 m (1250 trees per hectare). The experiment was established in a randomized block design, in four replications, with 5 trees per plot. In 2006-2009, records of vegetative growth, abundance of blooming, yield, and fruit weight were taken. The first significant yield was achieved in the third year after planting. In 20082009 trees of 'Shiro' had an abundant yield (48.5 kg •tree-1). 'Shiro' produced a significantly higher yield compared to other cultivars. There were no significant differences between 'Amers' (27.3 kg •tree-1) and the Japanese plum cultivars 'Kometa' (29.2 kg-tree-1) and 'Skoroplodnaja' (21.5 kg •tree-1). Japanese plum fruits were significantly smaller compared to the European ones. The cultivar 'Amers' had the heaviest fruit (53 g). The Japanese plum trees had smaller fruits, and among the them, the cultivar 'Shiro' had the largest fruit (44 g). The observations showed that 'Shiro' produced higher yields, gave large fruits, and had intensive blooming, but the growth of the trees was very strong.