SUMMARYDequalinium chloride is a topical antiseptic, whose use may be attended by skin necrosis. Since microcirculatory changes are an early and distinct manifestation of tissue injury, the tissue damaging effect of dequalinium chloride on the microcirculation was examined.The immediate vascular reactions were studied by vital microscopy of the hamster cheek pouch and the late effects were visualized by microangiography of the rabbit ear. An aqueous solution of dequalinium chloride in concentrations well below those used in clinical practice induced severe microcirculatory disturbances.