At Fruit Research Institute in a ak, major objectives of the work on breeding new sour cherry (Prunus cerasus L.) cultivars are high cropping, large, high-quality fruits and resistance to causal agents of diseases and pests. As a result of the planned hybridization, more than 10,000 hybrid seedlings have been developed from about 40 cultivars within more than 110 parental combinations, among which are ' a anski rubin' ('Shasse Morello' x 'K r ser Weichsel') and ' umadinka' ('K r ser Weichsel' x 'Heimanns Konserven Weichsel') which have been named and released. Ten-year study of 11 hybrids, selected from the population of about 3,000 hybrid seedlings, gave four hybrids which have been singled out as elite (III/23, III/31, II/40 i XII/57). These hybrids are currently under procedure of being released as new cultivars. The paper presents two-year results of the study of ripening time, pomological properties, biochemical composition of fruits, and field resistance to causal agents of diseases and pests attacking the above named genotypes which were compared to standard cultivar 'Heimanns Konserven Weichsel'. In the studied hybrids, fruit weight, soluble solids content and sugars content were higher than in standard cultivar. In addition, they exhibit substantial field resistance to causal agents of brown rot (Monilinia laxa /Ader et Ruhl./ Honey ex Whetz.), cherry leaf spot (Blumeriella jaapii (Rehm.) v. Arx.), shot-hole (Clasterosporium carpophilum (Lév.) Aderh.) and cherry fruit fly (Rhagoletis cerasi L.) attack.