Based on the available pedigree data, the population of přeštické černostrakaté breed was analyzed. The basic population parameters characterizing the genetic variability of the breed were calculated. To separate the effect of inbreeding over the past generations compared to the effects that have evolved over the distant past, the total inbreeding has been divided into new, achieved in the last 4 years and old inbreeding. In addition to the effect of the individual’s inbred coefficient, the influence of inbreeding was also evaluated by the father and mother. Subsequently, the influence of inbreeding depression on performance of traits: average daily gain (Prir), lean meat (LM), fat height (bacon), total number of born piglets (SV), live piglets (SŽ), weaned piglets (SD) and farrowing interval (MD) were analysed. The maximum number of generations with known ancestors was 14. On average, all the animals had known ancestors of the fifth generation. The average total inbreeding was 4.41 % with an average increase between the last generations of up to 1.58 %. In recent years, the inbreeding coefficient has been growing steadily with a higher share of inbreeding in the last four generations. The effect of inbreeding was statistically significant but low. Greater influence was observed in reproductive traits (especially for farrowing interval and all born piglets). The correlation coefficient between individual’s new and total inbreeding coefficient was 31 %