none The community of arthropods in rice paddy was divided on the basis of nutritional relationships into five guilds, i. e., phytophages, parasitoids, predators, detritivores and others, and the effects of two indica lines (TT9-3 and TT9-4) of transgenic Bacillus thuringiensis rice (Bt rice) with a fused gene of cry1Ab/cry1Ac on this community were investigated and evaluated in terms of guild dominance, family composition and dominance, as well as the usual indices, at four locations for two years. The control community was that of an untransformed (IR72) rice crop. Significant differences in the dominance of some superior families in phytophagous, parasitoid and detritivorous guilds were found between B. t. rice plots and the control. For example, the dominance of the Braconidae and Ichneumonidae in B. t. rice plots was sometimes markedly lower than in the control. In most cases, however, there were no significant differences in guild dominance, family composition and dominance or common community indices such as species richness, Shannon-Wiener diversity index, evenness index and dominance index. The temporal dynamics of B. t. rice plots and the control were also similar. Meanwhile, most of the dissimilarities between phytophagous sub-communities, parasitoid sub-communities, predator sub-communities and arthropod communities as a whole in B. t. rice plots and the control were apparently low. It was apparent that planting of B. t. rice generally did not have any marked negative effect on the rice paddy arthropod community. Ecology; Habitat; Man made habitat Arthropoda; Community structure; Cultivated land habitat; Rice paddies, effect of transgenic rice