We reported a case of histiocytic lymphoma associated with monocytic leukemia in a 55-year-old male. The patient showed numerous pruritic erythematous papules and nodules on the entire body surface, cervical and inguinal lymphadenopathy. Biopsy specimen frorn a nodule on the trunk showed widely scattered patchy infiltration of abnormal, hyperchromatic polymorphous histiocytes. The bone marrow aspirate smear revealed many atypical cells which have monocytic nuclear and cytopla,smic characteristics. Some cells are large and have serrated borders. Monoblast nuclei exhibit extreme irregularity and are folded.