Many factors can interfere with the therapeutic results for acute renal allograft rejection with anti-CD3 and CD4 MAbs. 1. When should we begin using MAbs and what about Scr levels while using MAbs? First-line treatment may be superior to rescue treatment; the earlier the better. 2. What is the level of blood concentration of CyA when rejection occurs? If the concentration of CyA is poor, the prognosis may be worse. 3. How do we maintain the dose of CyA during antirejection treatment with MAbs? Maintained use of CyA can play a coeffective role during antirejection treatment with MAbs. 4. What about the inhibiting degree of T-lymphocyte subsets after using MAbs? Whether CD3+ and CD4+/CD8+ decrease or not following the use of MAbs, the T-lymphocyte subsets may interfere significantly with the therapeutic results of MAbs. 5. The combined use of CD3 and CD4 MAbs seemed to get better results, especially for the intractable rejection cases. If we take care of the factors as referred to above, we may get a better therapeutic effect in reversing acute renal allograft rejection episodes with anti-CD3 and CD4 MAbs.