This paper discusses the use of cell interleaving (CI) to compensate for cell losses in VBR video transmission. To bound the delay due to CI, we propose a CI method with variable interleave unit length. Since the effectiveness (gain) of CI depends on the additional redundant information amount (redundancy) and delay, the optimum redundancy which maximizes the gain and the relation between the delay and the gain need to be studied. Thus, the gain of the proposed CI when it is applied to VBR video transmission is analyzed as a function of redundancy and delay tolerance. The analysis yields the following results: In the case where 50 VBR video sources are multiplexed, the tolerated delay should be larger than 20 ms to yield positive gain, and provided that tolerated delay is 33 ms (one video frame interval), the optimum redundancy is achieved at around 0.22 and the maximum gain is 0.091. The gain becomes smaller as more video sources are multiplexed. In case 200 sources are multiplexed, the gain is negative even if tolerated delay is 33 ms (one video frame interval). © 1998 Scripta Technica, Electron Comm Jpn Pt 1, 81(10): 81–90, 1998