Rituximab (Rituxan; IDEC Pharmaceuticals, San Diego, CA, and Genentech, Inc, San Francisco, CA) is a chimeric anti-CD20 monoclonal antibody that targets mature B cells and most B-cell malignancies. Rituximab was the first monoclonal antibody to be approved for therapeutic use for any malignancy. Its approval was based on a single-agent pivotal trial in patients with indolent B-cell lymphoma, in which 166 patients were enrolled from 31 centers in the United States and Canada. The overall results of the trial have been previously reported; additional aspects of the trial (eg, pharmacokinetics) have been reported separately as well. The current report includes an update, expansion, and synthesis of data from the single-agent pivotal trial of rituximab.