Abstract. Sow reproduction influences farm economy and can be considered as key factor of pig production efficiency. The aim of this study is to evaluate the effect of wean to standing reflex interval on the total number of piglets born and correlated number of piglets born alive and number of piglets weaned. Study was performed on crossbreed of Large White and Landrace sows originated from a commercial farm thus our results describe the real effect under commercial conditions. The results indicate that wean to standing reflex interval influence the litter size traits negatively if this interval is longer than 108 h. Highest differences was detected between 84 and 108 h of wean to standing reflex interval where decreasing about 2.8 total number of piglets weaned (P≤0.01) was found. Mutually only small effect of number of inseminations was detected.