The PHT1 promoter::GUS fusion gene was constructed and introduced into Arabidopsis and rice by Agrobacterium-mediated transformation. Strong P-glucuronidase (GUS) activity was detected in roots and showed phosphate starvation induction both in Arabidopsis and rice. In contrast, GUS activity in aerial tissues such as those of the leaf and stem was low. In situ GUS staining of root tissue indicated that PHT1 was expressed in root hairs and the outer layer of the main roots, but not in root tips. The PHT1 promoter has a desirable character for biotechnological transgene expression in monocot rice plants.