This study was conducted under irrigated conditions to determine the effects of seeding rate and harvest stage of pea (Pisum sativum ssp. arvense L. Poir), which was used here as a companion crop, on the hay yield, red clover (Trifolium pratense L.) densities and weed densities. Field studies were conducted as two separate experiments between 2004- 2008. Red clover was sown together with pea at the rate of 20, 40, 60 and 80 seed $m^ {-2}$. Plots were cut either at the 50% flowering stage for pea or when 70% of pea pods reached at typical lenght. Also, red clover was sown alone as a control and harvested at 50 % flowering stage. In the establishment year, companion crop had increasing effect on hay yield. Regarding total yield at the end of the 3 years, it is suggested that red clover was able to sown with pea at the seeding rate of 40 or 60 seed $m^ {-2}$ and it was harvested at 70% of pea pods reached typical lenght.