['Induction of delayed hypersensitivity reactions by red tattoos has been occasionally reported. Little is known about the inks used. Azo pigments have been implicated in some instances, but there is only one reported case involving quinacridones.', 'To describe the clinical and pathological features and outcome of skin reactions induced by red tattoo pigments.', 'Six patients with a cutaneous reaction induced by a red tattoo pigment underwent biopsy and prick and patch testing with the inks supplied.', 'We observed seven reactions in the 6 patients. Histology showed various patterns: three lichenoid, two eczematous, and two pseudolymphomatous. Five reactions occurred with azo pigments, and two with quinacridones, in both cases with Violet 19 and Red 122. Four inks were tested. Only one patch test gave a positive result at a late reading (day 7). Prick tests gave negative results. The reactions required various treatments, including laser treatment for 2 patients. Activation of the reaction in 1 case was transient.'] Do azo pigments and quinacridones induce delayed hypersensitivity in red tattoos?