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In spite of the extremely low phosphorus (P) availability in soils of the Alxa Desert region (Inner-Mongolia, China), many shrubs grow well there. The objective of this study was to investigate the status of inorganic phosphorus (Pi) fractions in the rhizosphere of xerophytic shrubs. For all five selected shrubs, soil pH in the rhizosphere decreased by 0.4-0.8 units and the total P concentrations were greater than those ill the corresponding bulk soils. In the rhizosphere of Reaumuria soongorica, Olsen P concentration was lower than that in the bulk soil. In general, the order of Pi fractions was Ca-10-P > Ca-8-P > Al-P > Fe-P > Ca-2-P > O-P. The concentrations of all Pi fractions varied significantly with rhizosphere and corresponding bulk soils. The results of stepwise regression showed that Olsen P concentration in rhizosphere and bulk soils was contributed by different Pi fractions. The correlation analysis showed that: the relationships between Pi fractions differed between rhizosphere and bulk soils. These results indicated that the soil Pi fractions are significantly affected by root activities, differing between the rhizosphere and bulk soils, and different xerophytic shrubs exhibited significantly different effect on soil Pi fractions. (C) 2008 Elsevier Ltd. All rights reserved.