In order to evaluate the effects of initial seed phosphorus content (through different phosphorus use on parent plants) and planting density on growth properties and yield of three barley (Hordeum vulgare L.) cultivars, experiment was conducted as a factorial split plot based on randomized complete block design with three replications during 2011-2013 in the Dryland Agricultural Research Institute, Maragheh, Iran. The first factor was cultivar (A₁= Sahand, A₂= Abidar and A₃= Dayton), second factor was primitive seed phosphorous content that was applied previous year on parent plants (C₁= 0, C₂= 15, C₃= 30 and C₄= 45 kg ha^-1), and third factor was seed rate (B₁= 300, B₂= 400 and B₃= 500 seed m^-2). Also the content of seed phosphorous percentage after its application in different amounts in the parent plants last year was measured. Results indicated that due to using different amount of phosphorous fertilizers, the amount of phosphorous in the produced seeds had a significant difference. In addition, the results showed that cultivar, seed rate and seed phosphorous content were significantly effective on some measured traits. Interaction of cultivar×seed rate×initial seed phosphorous content showed that treatment of A₃×B₃×C₃ (Dayton with the seed rate of 500 seed m^-2 and 30 kg ha^-1 P applied for parent plants), had the highest 1000-seed weight (40.2 gr), productivity degree (92.6), biological yield (3868 kg ha^-1) and seed yield (2463 kg ha^-1). The effect of seed phosphorous indicated that Dayton had the highest initial phosphorous in the seed. The seed phosphorous was also effective in enhancing dry matter as well as seed yield ultimately, it was also essential in improving the early establishment, growth and yield. ‏This research showed that the amount of seed phosphorous, cultivar and seed density contributed to yield increase.