The immune system has the potential to either attenuate tumor growth or to promote tumor progression. The goal of cancer immunotherapy is to shift the balance in favor of tumor immunosurveillance, so that the immune system can recognize the tumor, eliminate it, and prevent its recurrence. Bendamustine plus rituximab is generally considered effective and safe in patients with previously untreated chronic lymphocytic leukemia (CLL) and indolent non-Hodgkin lymphomas. To evaluate the effects of bendamustine-rituximab and rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) on the recuperation of immune system, we analyze the distribution of CD4+ and CD8+ T cells, B cells, and NK cells in peripheral blood of 18 patients who received 4-6 cycles of rituximab-bendamustine (BR) or six R-CHOP before therapy and 6 months after completing treatment. Our results indicate that lymphocyte recovery is impaired in patients with chronic lymphocytic leukemia and indolent lymphomas treated with bendamustine plus rituximab. Low CD4 T cells (<200 cells/μl) induced by bendamustine (BR) suggest prophylaxis should be applied against opportunistic infections. Asymptomatic EBV and CMV reactivations support a negative effect of BR on the immune system. If cellular immune therapy such as lymphokine-activated killer (LAK) or effector lymphocytes infusion is planned, regimes other than BR should be the first choice.