The effects of a mid-laying period reduction in dietary protein level on productive performance was studied with 576 individually caged Single Comb White Leghorn hens from four strains. The hens on treatments 1 and 2 received diets that contained by calculation 17 and 15% protein, respectively, between 143 and 507 days of age, while those on treatment 3 received 17 and 13% protein diets from 143 to 325 and 326 and 507 days, respectively. For treatment 4, diets containing 15 and 13% protein were given during the same periods as for treatment 3. Egg quality measurements were taken on eggs laid over 5-day intervals when the birds were 182, 252, 316, 380, 436, and 485 days of age. Dietary protein level had no significant effects on feed intake, mortality, body weight, egg production, egg grade, specific gravity, egg weight, Haugh units, or blood spots. Protein intake had no effect on the 507-day body weights and on hen-day egg production, except for a small decrease for treatment 4, although the intakes of protein, leucine, and lysine were lower for treatments 3 and 4 between 326 and 507 days of age than the NRC requirements. Level of dietary protein had no effect on kg feed/dozen eggs but had a significant (P<.01) effect on kg feed/kg eggs. Strain of bird had a significant effect on body weight, egg production, specific gravity, egg weight, Haugh units, and blood spots at 485 days. There were no significant protein level X strain interactions.