Cutaneous patch and plaque lesions, and erythroderma may suggest mycosis fungoides both clinically and histopathologically in HIV+ patients. However, in some cases, this diagnosis is questionable. Five such cases are presented. When we compared these cases with cases of mycosis fungoides unassociated with HIV infection, we found less concordance among dermatopathologists in making a histopathological diagnosis, a greater proportion of CD8 than CD4 T cells in the cutaneous infiltrates, and no instances of demonstrated clonality of the cutaneous T-cell infiltrates in the HIV+ group. We conclude that CD8 T-cell predominant dermatoses may simulate mycosis fungoides in HIV+ patients.