A 41-year-old HIV-positive man presented with a 2-month history of a generalized pruritic rash, which had started on his feet. Patch testing made a diagnosis of allergic contact dermatitis to the textile dye basic red 46, likely to have been present in his dark-blue-coloured socks. Complete resolution of his symptoms occurred with avoidance of these socks. The patient had developed allergic contact dermatitis with a low CD4 T lymphocyte count of 361 cells/microl (normal range 410-1545 cells/microl). This raised the question of the level of CD4 count necessary for an individual to develop allergic contact dermatitis to an allergen, given its role in delayed hypersensitivity. It was concluded that a low CD4 count as a result of HIV infection does not decrease the ability of an individual to develop allergic contact dermatitis. Whereas the effector role in delayed type 4 hypersensitivity reactions is mediated by CD4 T lymphocytes, in allergic contact dermatitis it appears that CD4 T lymphocytes have the suppressor role, with CD8 T lymphocytes having the effector role.