Two field experiments were conducted during 2006 and 2007 summer growing seasons at Ismailia Agric. Res. Station, to study the effect of phosphorus treatments (soil at the rate of 0, 31 kg P₂O₅ and foliar application of 2% P₂O₅) as well as bio-fertilizer treatments (0, Phosphorein alone, Phosphorein + Rizobactrein, Phosphorein + Microbein and Phosphorein + Nitrobein) on yield, yield components and seed oil percentage of peanut (Arachis hypogaea, L.) Giza 6 cultivar. Results indicated that soil application of 31 kg P₂O₅/fad. gave the highest values for number and dry weight of nodules/plant (mg), phosphorus content, number of pods/plant, pod yield/plant (g), seed yield/plant (g), 100 – pod weight (g), 100 – seed weight(g),  pod yield/fad (kg) and seed yield/fad. as well as seed oil percentage in both seasons. Also results showed that all inoculating treatments increased number, dry weight of root nodules and phosphorus content but with varying degrees compared with inoculation with phosphorein alone. In that respect bio-fertilizer treatments were descendingly arranged as follow: Phosphorein + Microbein > Phosphorein + Notrobein > Phosphorein + Rizobactrein. Co-inoculation with Phosphorein + Microbein exhibited superiority for the above mentioned parameters over the other co-inoculation treatments. Similar findings were obtained for yield and its components when inoculation with Phosphorein + Microbein produced pod yield/fad. higher 38.14 and 39.58% above the control treatment in both seasons. Interaction effect between phosphorus and bio-fertilizer treatments was significant for all studied attributes in both seasons, dry weight of nodules/plant, phosphorus content, seed yield/plant, 100 – seed weight and shelling percentage. It was shown that soil application of 31 kg P₂O₅ with combination of Phosphorein + Microbein gave the highest values for yield and yield attributes in both seasons.