We showed in this study the longitudinal changes of the B-cell counts in patients with steroid-dependent nephrotic syndrome (SDNS) treated with cyclophosphamide (CPM) and mycophenolate mofetil (MMF). In our case with SDNS, this combined therapy not only decreased B-cell counts but also increased CD5+CD19+ (CD5+B)/ CD5-CD19+ (CD5-B) cell ratio. Recurrence was not observed when an elevated CD5+B/CD5-B cell ratio was maintained even after the B cells increased. Therefore, this ratio might be more important than the whole B-cell counts. The changes of this ratio could be a good predictor of the clinical course of the patients treated with B-cell targeting therapy.