The use of immunotherapy in the treatment of non-Hodgkin lymphomas has improved response rates and survival in this population. With widespread rituximab use and longer-term follow-up of patients receiving rituximab, infectious complications are increasing. These complications are of great concern in the AIDS-related lymphoma population. We review the data on activity and infectious toxicity of rituximab to date and as it pertains to the treatment of AIDS-related non-Hodgkin lymphoma and Multicentric Castleman's disease.