Tacrolimus (TAC) is an immunosuppressive macrolide of the calcineurin inhibitor (CNI) group that is widely administered following organ transplantation. In 1989, Takabayashi K. et al. studied the effect of TAC on a murine model of SLE, and showed that it prolonged lifespan, reduced proteinuria, and prevented the progression of nephropathy, although it had no appreciable effect on the levels of anti-dsDNA antibodies. More recent small-scale studies have shown that TAC may be an effective treatment for nephritic syndrome and LN8-11. However, there is little clinical experience in the use of TAC for treatment of LN, especially for LN with severe renal disease, and limited knowledge of the comparative efficacy of TAC and other therapies.