Livedo reticularis is a mottled bluish discoloration of the skin which occurs in a netlike pattern and is not a diagnosis in itself, but is a nonspecific reaction pattern. It may be classified as idiopathic and secondary livedo reticularis. Decompression sickness can occur during decompression after diving into deep sea water or during a rapiid ascent from sea level, and is one of the many causes of the secondary livedo reticularis. We report a case of livedo reticulris which developed in a patient with decompression sickness. A biopsy from the purpuric patch revealed an unusual histopathologic finding that resembles those of bullae and sweat gland necrosis in drug induced coma. (Korean J Dermatol 1999;37(6) : 804~806)