A new hereditary physical urticaria, dermo-distortive urticaria (DDU), is described in a Christian Lebanese family. DDU is characterized by the appearance of pruritic, erythematosus, edematous, cutaneous swelling confined to the stimulated area in response to stimuli that vibrate or stretch the skin in a repetitive manner. The lesions appear within several minutes after stimulation and disappear within an hour. Extensive stimulation causes not only local urticaria but also a systemic response of faintness, headache, and facial erythema. Other than these annoying reactions, no other morbidity is associated with this disorder. While this disorder is certainly uncommon and its manifestations are more annoying than life threatening, it may be an important example of a heritable defect of inflammation control mechanisms. Although the mediator for the urticaria and systemic response was not isolated, a likely candidate is histamine. Computer analysis of the phenotype of 219 relatives in 6 generations shows that DDU is transmitted as an autosomal dominant trait with high penetrance. DDU is clinically distinct from hereditary angioneurotic edema, pressure urticaria, and dermographia. It is similar to vibratory angioedema (VA), but sufficient evidence to prove that DDU and VA are identical is not available.