Fourteen patients with metastatic renal cell carcinoma (RCC) were treated on a Phase II trial with arsenic trioxide (As2O3). Eligible patients had metastatic renal cell carcinoma with bidimensionally measurable disease, a Karnofsky performance status of at least 70%, life expectancy of greater than three months, and no evidence of brain metastases. Arsenic trioxide was given intravenously at a dose of 0.3 mg/kg/day for five consecutive days every four weeks. The most common toxicity observed was grade II elevation in liver function tests (36%), anemia (21%), renal insufficiency (14%), rash (7%), and diarrhea (7%). Best response was stable disease in 3 patients with one patient remaining on study at 8+ months At the dose and schedule used in this trial, arsenic trioxide did not achieve a complete or partial response in metastatic renal cell carcinoma.