A restriction endonuclease from Hemophilus influenzae. II. Base sequence of the recognition site.

Discovery of the first type II restriction enzyme (HindII).

Smith shared the 1978 Nobel Prize in Physiology or Medicine with Werner Arber and Daniel Nathans "for the discovery of restriction enzymes and their application to problems of molecular genetics."

Also: Smith H.O., Wilcox, K.W. , "A restriction enzyme from Hemophilus influenzae. I. Purification and general properties," J. Mol. Biol. 51 (1970) 379-391.