Mucous membrane plasmacytosis is a rare, often idiopathic, inflammatory disorder that frequently presents as an erythematous, velvety, or lobulated plaque on a mucosal surface. While mucous membrane plasmacytosis often runs a benign course, plaques are known to erode, ulcerate, and bleed. Moreover, according to a recent review of mucous membrane plasmacytosis, treatments of this disorder are inconsistently successful. We report a case of erosive, hemorrhagic mucous-membrane plasmacytosis of the lips treated successfully with cryotherapy. To the best of our knowledge, this case represents the second case of mucous membrane plasmacytosis successfully treated with cryotherapy. The long term response of our patient's condition to cryotherapy with no functional side effects may warrant further study of this technique for severe erosive mucous membrane plasmacytosis.