Abstract: Real-world objects are inherently spatially and temporally referenced.As a result,indices that efficiently support queries on the spatio-temporal extents of objects are needed.In contrast,the past indexing researches have made progress in largely separate spatial and temporal streams.This paper is focused on deriving efficient access methods for spatio-temporal objects in GIS.In this paper we extend the well-known R-tree method to handle spatio-temporal object.The resulting access method,termed(spatio-temporal box) STB-tree,differs from the R-tree in that it stores additional information in the entries.The structure and the algorithm of STB-tree are proposed in detail.