The purpose of this study is to determine the tolerance and toxicity of single agent Rituximab in patients with AIDS-associated NHL and the effect of Rituximab on the peripheral blood lymphocytic subsets and HIV viral load in patients with AIDS-associated NHL. Patients who have met the inclusion and exclusion criteria and have completed the pretreatment evaluation will receive Rituximab administered intravenously weekly. Each course will be given at the GCRC with observation for 24 hours after completion of drug administration. Initial enrollment will be limited to three patients. All three initial patients will be observed for at least two weeks following the last antibody infusion. If no more than one patient experiences dose-limiting toxicity, the remaining three patients will be enrolled. If at any time two patients have experienced dose-limiting toxicity, no further enrollment will proceed.