This paper proposes a condition-based algorithm for H.264/AVC 4x4 intra prediction. Exploiting high correlation existed in neighboring intra prediction modes, we propose the three conditions to skip the less possible candidates in doing Intra4x4 block mode decision. When compared to the 9 prediction modes in the full search algorithm, the proposed algorithm can complete a 4x4 intra prediction using 4.4 prediction modes operation in average. The simulation result shows that the proposed algorithm can reduce computational complexity up to 44% at the cost of less than 0.1dB PSNR loss in average.