Cyanoethylation of 5,5-disubstituted hydantoin reported by one of us (Hsing Chi-Yi) previously (1955) appears to have been overlooked by Masatsue Sato^[2],whose results announced recently are essentially similar to ours.5,5-Dimethyl hydantoin can be monoor dicyanoethylated by the action of alkaline catalyst.The cyanoethylated products can be hydrolyzed by means of 2:1 hydrochloric acid or alcoholic hydrogen chloride to the corresponding acids or esters.The monocyanoethylated hydantoin was hydrolyzed by means of 60% sulphuric acid,one of the product was definitely proved to be β-amino propionic acid.Consequently the position of the cyanoethyl group is located at position 3 as assigned by Sato through other means.Tn view of the antitubercular properties of certain hydrazides and hydrazones,series of β-5,5-disubstituted hydantoin propionyl hydrazides were prepared from the corresponding esters.The hydrazides were then condensed with acetone to the hydrazones,most of the resulting products being crystalline substances,the xields ranging from 70 to 90%.