Objective To observe the temporal and spatial expression of Smad7 during human tooth germ development and evaluate the effect of Smad7 on tooth germ development.Methods The expression of Smad7 and its changes at different stag- es of human tooth germwere detected by using immunohistochemical staining.Results Smad7 was expressed at all stages of tooth germ, but the distribution patterns at various stageswere different. It indicated thattemporal and spatial expressingmode of Smad7 during human tooth germ developmentwas specific, whichwas similartothat ofTGF-βand its signal transducerSmad2/3.Conclu- sion Smad7 might play an important role in TGF-βintracellular signaling for modulating the differentiation of ameloblasts and odontoblasts.