The aim of this study was to find out is it possible to presume success of boars sperm cryopreservation, based on controlled exposure to heat stress and to investigate in vitro quality parameters of frozen/thawed sperm of previously selected 6 boars with good results (group 1) and 6 boars (group 2) with bad results on thermo resistance test (TT). In this investigation, ejaculates of 12 chosen of 75 AI boars (Landrace, Large White, Pietrain and Durock breeds) from SVC Velika Plana (Serbia) were

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... sed. Tolerance to heat stress was performed by Schaetz (1963) method. Ejaculates were extended with Androhep plus (1:1) and kept during 60 minutes on 41 o C. In cryopreservation of boars semen Westendorf et al. (1975 ) method, modified by Bwanga et al. (1990. Very significant changes of progressive motility rate were observed after spermatozoa exposure to controlled thermal stress. High correlation coefficient of progressive motility rate of both groups of boars, but higher in group 2 for progressive motility rate after thawing and after heat stress treatment was established. Average progressive motility rate of all 12 boars did not differ before and after thawing. Presence of boars of all breeds represented in the SVC (Large White, Landrace, Duroc and Pietrain) in both quality groups confirms the assumption that suitability for cryopreservation of sperm is individual trait. According data analysis, sperm deep freezing success requires previous selection for potential donors, which have to be consider standard quality parameters testing and controlled stress exposure tests.