Because nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) express CD20, rituximab may be used as a nonmutagenic treatment option to avoid late toxicities in this rather indolent entity. Between 1999 and 2004, the German Hodgkin Study Group (GHSG) investigated the activity of rituximab (375 mg/m(2) in 4 doses) in a phase 2 trial in 21 relapsed or refractory NLPHL patients. The initial diagnosis of NLPHL was confirmed in 15 of the 21 enrolled patients by reference pathology. The remaining cases were reclassified as Hodgkin lymphoma transformed to T-cell rich B-cell lymphoma (TCRBCL; n = 2) or CD20(+) classical Hodgkin lymphoma (cHL; n = 4). In NLPHL patients the overall response rate was 94%, including 8 complete remission (CR) and 6 partial remission (PR). With a median follow-up of 63 months (range, 3-84), the median time to progression was 33 months, with the median overall survival (OS) not reached. Thus, rituximab is highly effective in relapsed and refractory NLPHL. This study is registered at http://www.klinisches-studienzentrum.de/trial/285.