In 1967, 18 spring wheat varieties (Triticum aestivum L. em Thell.) were grown in the field at Bozeman, Montana, and sprayed on three dates with low rates of 2-chloro-4,6-bis (ethylamino) -s-triazine (simazine).The simazine treatments significantly affected both yield and percent protein. Yields decreased as rate of simazine increased and as wheat plants were more mature when treated. The May 16 and June 16 simazine treatments resulted in grain protein about 2% higher than the control, but this increase was accompanied by a corresponding decrease in yield of grain.A highly significant r value of 0.77 between grain protein and the grain to straw ratio suggests that grain protein is heavily dependent on total foliage production.