Dwarf White Leghorn pullets provided 0.033% Protamone from one day of age had higher average body weight, feed consumption, and cloacal temperature than did control dwarf pullets at four weeks of age. The difference in feed consumption between the two groups continued to increase, while the difference in body weight and cloacal temperature remained constant up to 16 weeks of age; at 24 weeks of age control dwarfs had slightly higher average body weight and cloacal temperature. Feeding Protamone did not affect age at sexual maturity or rate of increase in egg production, but did result in a lower yolk weight, had no effect on yolk color and total egg weight, and gave a higher egg specific gravity at 24 weeks of age.Protamone feeding at 0.033% level from 24 to 44 weeks of age decreased egg production and increased feed consumed per hen-day and per dozen eggs, regardless of whether or not they received Protamone from 0 to 24 weeks of age. Egg weight was not affected by feeding Protamone from 24 to 44 weeks of age; however, eggs produced during that time were slightly smaller if the pullets were fed Protamone from 0 to 24 weeks of age, although this may not have been a true treatment effect. Yolk weight and yolk color at 44 weeks of age were not significantly affected by any treatment. Egg specific gravity was higher at 44 weeks of age if the eggs were from pullets fed Protamone from 24 to 44 weeks of age.Reversing the treatments and reducing the Protamone level to 0.011% from 44 to 64 weeks of age gave inconclusive results, although feed conversion appeared to be adversely affected while egg specific gravity seemed to be enhanced by the Protamone feeding.