This paper reviews the syndrome of contact urticaria in terms of curre
nt knowledge regarding pathophysiological mechanisms. The three mechan
istic categories into which contact urticants are grouped include: (1)
immunological contact urticaria, (2) non-immunological contact urtica
ria and (3) uncertain-mechanism-mediated contact urticaria. Within thi
s schema, the clinical manifestations, diagnosis and therapy of contac
t urticaria are presented.