CD20 positive T-cell lymphoma is extremely rare. Most reported cases are nodal peripheral T-cell lymphomas (PTCLs) or rarely lymphoma involving extranodal sites. Only two cases of CD20 positive T-cell lymphomas involving the skin have been previously reported and were classified as PTCL - not otherwise specified. We present a case report of a 53-year-old man with CD20 positive mycosis fungoides (MF) involving the skin and an inguinal lymph node. The patient presented with erythematous patches and plaques of the right lower extremity and was found to have an enlarged inguinal lymph node 2 years later. Flow cytometric immunophenotyping of the lymph node aspirate showed a CD2+/CD3+/CD4+/CD5+/CD7-/CD8- T-cell population with CD20 co-expression. Molecular studies by polymerase chain reaction demonstrated clonal T-cell receptor gamma chain gene rearrangement. Immunoglobulin heavy and light chain gene rearrangements were not identified. To our knowledge, this is the first case of CD20 positive MF involving a lymph node to be reported in the literature.