Allergic contact dermatitis due to a polyurethane elastomer (spandex) Is reported. The dermatitis presents a characteristic distribution over the back, corresponding to the spandex-containing portions of bras. In each case the patients also have positive closed patch-test reactions to the rubber accelerator mercaptobenzothiazole. K is postulated that this chemical radical or a closely related chemical structure is used in the manufacture of spandex.