Non-Hodgkin's lymphomas (NHL) involving the vulva are rare. We report the clinicopathologic and immunohistochemical findings of six cases of vulvar NHL. The age of the patients ranged from 43 to 71 years (mean 60 years), and 5 presented with a vulvar mass. Two patients had neoplasms localized to the vulva, and two patients had a history of NHL that secondarily involved the vulva; in another patient the stage was unknown, and the sixth patient had stage IVA mycosis fungoides/Sezary syndrome involving the vulva. Each tumor was classified according to the revised European-American classification of lymphoid neoplasms: four were diffuse large B-cell lymphoma, one was peripheral T-cell lymphoma, and one was mycosis fungoides/Sezary syndrome. Two patients were treated with chemotherapy and radiotherapy, one patient received chemotherapy and phototherapy, one patient was treated with chemotherapy, and in two patients the treatment is unknown. Clinical follow-up, available for 4 cases, ranged from 7 months to 5 years. One patient with low-stage NHL responded to therapy, but relapsed and died of disease 2 years later. Two patients with generalized NHL that secondarily involved the vulva died of disease 7 months and 5 years, respectively, after the diagnosis of vulvar involvement was established. The patient with mycosis fungoides/Sezary syndrome is alive with disease at 4 years. The three patients in this study who died and our review of the literature indicate that NHL involving the vulva is usually an aggressive disease.