A number of instances have been reported in the scientific literature in which acute intoxication with halogenated oxyquinolines has led in some species to convlusions, often followed by death. The toxicity of repeated doses of clioquinol has been investigated extensively in the dog. The clinical syndrome induced in this species is characterized by anorexia, weight loss, extremem muscle weakness and emaciation. In some animals surviving this impairment of condition for several weeks, neuropathy of the central nervous system, but not of the peripheral nerves ensued. It is suggested that these toxicological manifestations are less dependent on the dose-level than on the degree of absorption. Some suggestions regarding the aetiology of the lesions are made.