We present the case of a young woman who developed renal failure of unknown cause, and after 2 months of maintenance hemodialysis developed livedo reticularis, retinopathy, and peripheral sensory neuropathy. The patient was subsequently shown to have primary oxalosis type I, a rare autosomal recessive error of metabolism characterized by accumulation of calcium oxalate crystals in the kidneys, eyes, skin, and other organs. Intravascular obstruction, caused by deposition of calcium oxalate crystals in cutaneous arterioles, is thought to be responsible for the ischemic livedo reticularis lesions observed in this patient. A method is described for measuring serum glycolate by isotope dilution gas chromatography-mass spectrometry (GC-MS). An approach to the diagnosis and management is also briefly mentioned.