Oral lichenoid reactions (OLR) can be caused by systemic drug exposure. To the best of our knowledge, this is the second report describing a case of OLR induced by rituximab administration in a patient with a diagnosis of non-Hodgkin B-cell lymphoma. After 5 doses of rituximab, a typical pattern of OLP was identified with bilateral and symmetrical lesions on the buccal mucosa and on the right lingual margin. This temporal relationship suggested a probable association between oral lesions and drug therapy. The clinical diagnosis of a rituximab-induced OLR was confirmed by an incisional biopsy reporting a histopathological result of lichenoid mucositis consistent with oral lichen planus. Because of the increasing use of rituximab, it is necessary to know and recognize this uncommon side effect.