Volume rendering in 3D ultrasound is a challenging task due to the large amount of computation required for real-time rendering. The shear-warp algorithm has been traditionally used for 3D ultrasound rendering for its effectiveness in lowering computing cost. However, this lowered computing cost does come at the price of reduced image quality due to (a) the presence of final warp interpolation, which smoothes out fine details and (b) sampling only at discrete slice locations, which introduces aliasing, e.g., staircase artifacts. For 3D ultrasound, we have merged pre-integration with the shear-image-order algorithm to overcome both limitations of shear-warp while still enjoying the computational savings. Pre-integration overcomes the aliasing artifacts while shear-image-order preserves details. We have also developed a technique to integrate shading coefficient into pre-integrated rendering. This pre-integrated shear-image-order algorithm, with slightly higher computation than what is required to support the shear-warp algorithm, improves the quality of the rendered image significantly. In this paper, we discuss the pre-integrated shear-image-order algorithm and present the results of subjective quality evaluation on several data sets. We have also analyzed how this algorithm can be implemented on an advanced digital signal processor (DSP) to achieve real-time performance.