A reduced level or complete cessation of sweating can be caused by a variety of factors affecting sweat glands directly or indirectly through alterations in their nerve supply. The most common presentation is the syndrome of heat intolerance with or without features of dysautonomia. An acquired idiopathic form of generalized anhidrosis is characterized by loss of sweating in the absence of any neurological features or destruction of sweat glands. Cholinergic urticaria has been associated with some cases of this acquired idiopathic form of generalized anhidrosis. A case of generalized absence of sweating without a neurological deficit is described, and the implications of heat intolerance are discussed.