Only two of our patients, two Japanese men, are diabetic, and only one of them was discovered to be ketonemic. Transient ketonuria was found, too, in two Japanese women, both of whom were dieting. None of them recovered by virtue of treatment of the diabetes only or from enhanced nutrition alone. The other 21 patients, all of whom had prurigo pigmentosa from as short a period of time as several months to as long as more than 10 years, never showed any alterations of a metabolic nature. The lesions in all of our patients, except for two non-diabetic Japanese who received no treatment, responded dramatically to minocycline or dapsone. It is likely that diabetes and transient ketosis are mere coincidence in patients with prurigo pigmentosa. No cause for the eruption could be identified in any of our patients.