A double-blind controlled trial of thyrotropin releasing hormone (TRH) 150 mg IM daily in 30 patients with amyotrophic lateral sclerosis is reported. The drug/placebo was administered for 2 months, followed by a 2-month “wash-out.” Evaluation of strength, functional ability, and respiratory functions was performed. A temporary increase in the strength of some muscles was detected following the administration of TRH, but no change in functional performance was noted. Neither the patients nor the investigators believed the effects were of any marked clinical significance. The course of the illness was not altered.