Rubber flooring in dairy cows has been discussed controversially, because different studies found as well advantages as disadvantages regarding claw health. Until today little is known regarding the effect of rubber flooring on the reproductive performance of dairy cows. Therefore, the study aimed at comparing fertility and the milk yield of dairy cows on concrete or rubber flooring. Days to first breeding (DFB), days open (DO), services per conception (SC), heat detection rate (HDR), conception rate (first service; CR1st service) and the corresponding 100 days in milk (DIM) milk yield were evaluated for 139 lactation periods of 91 cows of the University Munich Livestock Center dairy herd. The cows entered the study as heifers and were housed on the same flooring system during their whole productive life. All cows underwent the same management, feeding, and climatic conditions. A mixed model procedure was used to analyse data. Cows on rubber (RSF) compared with cows on concrete flooring (CSF) showed less DFB (76.8/94.6; P<0.01), less DO (98.8/138.4; P<0.01), and no difference regarding SC (1.5/1.7; P=0.267). Furthermore, no differences regarding the 100 DIM milk yield could be established. The calculation of HDR (54.9%/27.9%) and CR1st service (39.4/29.4) showed also high advantages for the rubber flooring. It was concluded that rubber flooring affects an earlier onset of regular oestrus behaviour and improves the economically sensible fertility trait of calving interval by earlier pregnancy and less days open but does not cause higher milk yield.