High-dose bolus or continuous infusion interleukin-2-based therapy can cause capillary leak syndrome. Significant cardiovascular/hemodynamic events, including myocardial infarction, hypotension, pulmonary edema, and cardiac arrhythmia, have been described with such therapy. Concern over the toxicity of highdose interleukin-2 (IL-2) therapy has led to some clinicians excluding patients 70 years of age or over. We have treated 15 patients 70 years of age or over having an Eastern Conference Oncology Group (ECOG) performance status of 0 or 1, with therapy based on continuous infusion IL-2 18 MIU/sq m/24 hours for 72 hours. All patients underwent a pretreatment evaluation of cardiac status with a low-level stress or adenosine stress test. Cycles were typically repeated every 3 weeks for 4 cycles, then every 3-4 weeks thereafter. Patients were treated by oncology nurses in either the stem cell transplant (intermediate unit) or the oncology inpatient unit. Patient characteristics were: median age, 72 years (range, 70-83 years); tumor types: melanoma (10), kidney cancer (5); most common sites of disease: lung (11), lymph nodes (6), subcutaneous (3), liver (2); prior therapy included: none (8), outpatient IL-2 (5), other immunotherapy (4). Median number of cycles received: 3 (1-10). Most common toxicities were: fever, rigors, nausea, emesis, hypophosphatemia, and hypomagnesemia. Three patients required the use of dopamine for blood pressure support. Two patients declined further therapy. There were no treatment-related deaths. No patients required endotracheal intubation or transfer to an intensive care unit. One complete and 8 partial responses (60% response rate) have been seen. Responding sites include the lung, lymph node, intact kidney primary, and liver. Median survival has not been reached at over 14 months (range 3+-26+ months). Patients who are 70 years of age and older with an ECOG performance status of 0 or 1 are able to tolerate high-dose continuous infusion IL-2-based therapy and may respond to such treatment.