The effect of age at first farrowing in the reproductive traits of Black Slavonian pigs Black Slavonian pig is an autochthonous Croatian breed created in the second half of the 19th century. With the introduction of modern breeds and crossbreeds the population was drastically reduced, but the survival of the breed is no longer endangered. The breed is well suited for outdoor and traditional farming system. The aim of this study is to determine and analyze the influence of age at first farrowing on the reproductive traits of this breed. The study included all gilts (n = 285) under selection control in the period from 2013. to 2015. Number of piglets liveborn per litter gilts average was 5.90, and piglets stillborn the average was 0.94.The most weaned piglets (4.96) were observed at gilts whose age was up to 280 days, and the least was 3.92 at gilts aged from 431 to 480 days. Due to the different age of first farrowing between parameters: total of born piglets, the duration of lactation, weaned pigs and pigs who died during lactation were found only negligible differences (P> 0.05). The only significant difference was found only for the parameter of stillborn piglets, and this is a group farrowed for the first time, from age of 431 to 480 days and with more than 530 days (P <0.05), whereas among other groups parameter of stillborn piglets identified only negligible differences (P> 0.05). It can be concluded that the age of first farrowing did not have a significant effect on the reproductive performance of gilts Black Slavonian pigs (P> 0.05).