[en] An expression of γ-ray efficiency for large samples is proposed based on numerical integration of efficiencies over compositional point sources. The widely used expression on radial variation of HPGe efficiency for point source originally proposed by Noguchi et al. (Int J Appl Radiat Isot 32:17-22, 1980 [1]) was amended and a new expression was proposed. A comparison between the two expressions indicates that the newly proposed expression brings about an obvious improvement, and Self-absorption correction for a voluminous source is also given out by using the EID principle. The functional relationship between HPGe efficiency for γ-rays from a point source and the spatial position of the source was established. The results of this study can be applied in order to determine γ attenuation effects of unknown bulky samples with various shapes and materials. (author)