Aggressive mantle cell lymphoma has a poor prognosis with current therapy and occurs frequently in an elderly population which cannot receive stem cell transplantation. Newer aggressive therapies are needed. In this study, 25 consecutive previously untreated patients 65 years or older with MCL were enrolled in two sequential phase II trials. The program included fractionated cyclophosphamide 1,800 mg/m2 administered with doxorubicin, vincristine and dexamethasone (hyper-CVAD), alternating every 3 weeks with high doses of methotrexate and cytarabine (M-A) for up to 8 cycles. Cytarabine was given as 1 gram/m2/dose. Six of 14 patients tested (50%) presented with gastrointestinal (GI) involvement, but only one had GI symptoms. The overall response rate was 92% (95% C.I. 73-99) and the complete remission (CR) rate was 68% (95% C.I. 46-85). With a median follow-up of 17 months, the median FFS for the entire group is 15 months. Hematologic toxicity was significant but only 5% of the cycles were associated with grade 3 infection. Treatment-related death occurred in 2 patients. In conclusion, GI involvement by MCL is common in this age group. Hyper-CVAD alternating with M-A with adjustment of the cytarabine is an active regimen in this elderly group of patients with untreated MCL and the toxicity is manageable. Strategies for eradicating minimal residual disease are still needed.