To study phosphorus (P) depletion and soil pH changes at the root-soil interface (rhizosphere) and at the hyphae-soil interface, mycorrhizal and non-mycorrhizal white clover (Trifolium repens L.) plants were grown for 7 wk in two sterilized soils (Luvisol and Cambisol) in pots comprising five compartments: a central one for root growth, two adjacent compartments, separated from the central compartment by a nylon net of 30-mu-m mesh size, for growth of vesicular-arbuscular (VA) mycorrhizal [Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe] hyphae (hyphal compartments), and two outer compartments, separated from the hyphal compartments by a 0.45-mu-m membrane, which neither roots nor hyphae could penetrate (bulk soil compartments). Phosphorus was supplied as Ca(H2PO4)2 at a rate of 50 mg P kg-1 soil in the root compartment and 150 mg P kg-1 soil in the hyphal and bulk soil compartments. Nitrogen was supplied as (NH4)2SO4 at the rate of 300 mg N kg-1 soil uniformly to all compartments. In both soils, shoot dry weight and P uptake were much higher in mycorrhizal plants compared with non-mycorrhizal plants. Hyphae of VA mycorrhizal fungi contributed 70 % (Cambisol) or 80 % (Luvisol) to total P uptake of mycorrhizal plants. In the hyphal compartments, concentrations of both H2O-extractable soil P (Cambisol and Luvisol) and NaHCO3-extractable soil P (Luvisol) were decreased drastically. Soil P depletion profiles developed not only at the root-soil interface (rhizosphere), but also at the hyphae-soil interface and extended several millimetres from the hyphae surface into the soil. Likewise, the soil pH was decreased at the root-soil interface, in the hyphal compartment and also at the hyphae-soil interface. The results demonstrate that, similarly to roots, hyphae of VA mycorrhizal fungi have the ability to form a P depletion zone and a zone of altered pH in the adjacent soil. Thus, as well as at the root-soil interface, soil conditions at the hyphae-soil interface may also differ considerably from conditions in the bulk soil.