Hairy cell leukemia (HCL) is an uncommon chronic lymphoproliferative disorder and accounts for around 2% of all forms of leukemias. The association of HCL with other neoplasms, mainly non-Hodgkin's lymphomas, is well known. However, the simultaneous diagnosis of HCL and Kaposi's sarcoma is rare, with only few cases of such an association having been reported. We describe a 42-year-old male patient with a well characterized HCL and in whom HIV-negative Kaposi's sarcoma of the lymph node was detected.