Inclusion Criteria:

1. Histological confirmed, low-grade B-cell lymphoma except mantle cell lymphoma and
histologic transformation to DLBCL

2. CD20-positive

3. Ann Arbor CS III or IV

4. Lymphoma cell count in PB≦10,000/mm3

5. 20<=age<=69

6. ECOG PS 0-2

7. Bidimensionally measurable disease >1.5cm in a single dimension by CT scans

8. No prior chemotherapy, radiotherapy, interferon-alfa, or antibody therapy

9. Normal BM, hepatic, renal, cardiac, and pulmonary function

10. Written informed consent

Exclusion Criteria:

1. CNS involvement

2. Glaucoma

3. DM treated by insulin

4. Uncontrollable HT

5. AP, AMI

6. Positive HBs antigen

7. seropositive to HCV

8. seropositive to HIV

9. Interstitial pneumonitis, pulmonary fibrosis, or emphysema

10. Severe infection

11. Liver cirrhosis

12. Double cancer

13. Pregnant or lactating

14. Patients who desire auto PBST after CR

15. Patients treated with major tranquilizer or antidepressant