Abstract This report describes a patient who presented with extensive inguinal lymphadenopathy while taking quinidine for the treatment of arrhythmias. An excisional lymph node biopsy specimen demonstrated atypical, reactive, follicular hyperplasia. Immunologic assessment utilizing 20 monoclonal antibodies indicated a reactive process with follicles shown to be polyclonal B cell. The patient's adenopathy resolved within one month of discontinuation of quinidine and he remains well 15, months later. The histologic and immunologic findings as well as the clinical response are typical for a drug-induced reactive lymphadenopathy.