The molecular characteristics of partly purified sucrose synthase (NDP-glucose: D-fructose 2-α-D-glucosyltransferase, EC 2.4.1.13), extracted from the bird cherry (Prunus padus L.) leaves was elucidated. The sucrose synthase was successfully purified by using a four-step protocol including ammonium sulfate precipitation, dialysis, gel filtration on Sephadex G-150 and ion-exchange chromatography with the use of DEAE -cellulose. The analysed enzyme occurred in two isoforms (SuSyI and SuSyII ). The relative molecular weight of native isoenzymes was estimated to be 200 and 180 kDa, respectively. Isoform SuSyI contained two different subunits of 57.5 and 52.8 kDa, whereas the structure of SuSyII was consisted of identical 63 kDa subunits. Experimental data indicated that the structure of both SuSy isoforms was composed of three subunits.