The aim of this study was to analyze production and quality of semen in boars in an insemination centre. Experimental material consisted of 8,052 semen samples collected from 146 boars. During the period of 5 years, an analysis of semen parameters was conducted. The obtained data were divided according to age of boars at the time of semen collection. Results showed that boars between 8 months and 3 years of age reached higher levels of semen volume, percentage of abnormal spermatozoa and number of spermatozoa. Older boars had lower sperm concentration levels. The largest total number of spermatozoa and corrected number of spermatozoa were observed in boars between 13 and 36 months of age. Later, the production of spermatozoa decreased. Based on the results of the presented study, the age category of 13 - 36 months can be recommended to dominate in the herd of boars in the insemination centre.