The first case of oral hairy leukoplakia in an HIV-negative patient with multiple myeloma is reported. The patient is a 56-year old man who has had monoclonal gammopathy of undetermined significance since 1986 and has been treated for a symptomatic multiple myeloma since 1993. The clinical and histopathologic findings are typical for oral hairy leukoplakia, and Epstein-Barr virus was demonstrated with polymerase chain reaction technique. Although a relatively large number of cases of oral hairy leukoplakia has been reported in HIV-negative patients, both immunocompromised and immunocompetent, only a few of these patients have had a malignant hematologic disease.