Options for treating aggressive non-Hodgkin lymphoma (NHL) have expanded in recent years. In phase 3 clinical trials, giving rituximab with cyclophosphamide, vincristine, doxorubicin, and prednisone (CHOP) every 3 weeks (R-CHOP-21) has been associated with improved survival, without increased toxicity, in all patient groups studied. Giving dose-dense CHOP--CHOP every 2 weeks (CHOP-14)--has also proved appropriate for all patients 18-75 years old. Studies combining these approaches--dose-dense CHOP with rituximab (R-CHOP-14)--have shown improved survival over CHOP-14 in patients 60-81 years old. These results also indicate the importance of delivering chemotherapy at full dose and on schedule, which can improve survival in aggressive NHL. Effective delivery of dose-dense regimens requires granulocyte colony-stimulating factor support, which should also be considered for standard CHOP. A key question for the future is whether R-CHOP-14 is superior to R-CHOP-21.