The objective of this study was to assessed the percentage of viable spermatozoa of boar using by flow cytometry and by eosin-nigrosine staining. Fifteen fertile Přeštice black-pied boars of various ages (1- 5 years) coming from one AI centre were used in this study. Ejaculates (n=169) were collected using the gloved-hand technique during 3 years. The basic parameters of boar sperm quality were assessment and percentage of sperm viable spermatozoa were determined by flow cytometry using SYBR-14 and propidium iodide and by a supravital staining technique using the eosin-nigrosine stain mixture. According results, there is no statistically significant difference between the methods of determining the percentage of viable spermatozoa (p=0.95). A statistically significant correlation coefficient was found between the methods (p>0.05). In conclusion, on the basis of the results, it was found that both methods of determining viable spermatozoa enable to compare the integrity of boar spermatozoa membranes and thus to assess the quality of insemination doses.