Abstract: The hepatically produced isomers, URO I and URO III, are neuroprotectors capable of halting or mitigating the nervous system destruction in common neurological disorders. URO I protects neurons of the central nervous system from damage that would otherwise ensue from the neurotoxicity associated with the hepatic heme porphyrin precursors, delta-aminolevulinic acid and porphobilinogen. A method is disclosed to increase URO I to treat amyotrophic lateral sclerosis (ALS), stroke, encephalitis, meningitis, spinal cord injury and hereditary biochemical multiple sclerosis. Increases of URO III are also used to protect neurons in the peripheral nervous system in disorders including acute immunodeficiency syndrome (AIDS) related neuropathy, Guillaine-Barre syndrome and diabetic neuropathy.