Laying hens were placed on a diet containing 200 p.p.m. Sevin® (l-naphthyl N-methylcarbamate) for 1 week and then returned to uncontaminated feed. Tissues and eggs were analyzed at 3, 7, 8, 10, and 14 days by colorimetric procedures having a sensitivity of 0.1 p.p.m. No residues of Sevin were detectable in the breast, drumstick, gizzard, liver, skin, or eggs from hens sacrificed during the 14-day test period. Egg production remained normal, and the hens suffered no apparent ill effects from treatment.