The effects on soybean yield components of inoculation with arbuscular mycorrhizal fungus ( AMF) Glomus fasciculatum were investigated at different phosphorus levels. The level of root AMF colonization decreased a little when P levels increased. Mycorrhizal inoculation and increasing levels of P application had positive effects on yield components such as stem and root length, shoot and root dry weight, stem diameter, 1000-grain weight and seed yield per plant but not on legume numbers per plant. Both mycorrhiza inoculation and P treatments affected P and N concentrations of grain and roots of soybean. Mycorrhizal fungi decreased the need of P addition in growth medium by contributing to the demand of optimum phosphorus for growth of soybean.