The requirements of larvae of the rice weevil, Sitophilus oryzae (L.). for 8 rat-essential amino acids were determined in a cornstarch-based diet using a mixture of 15 amino acids. With a total amino acid level of 5.0%, the lowest concentrations that gave growth rates comparable to those obtained on the standard 15 amino acid diet were: L-arginine, 0.15%; L-histidine, 0.12%; L-isoleucine, 0.20%; L-leucine, 0.40%; L-threonine, 0.15%; L-trypto-phane, 0.04%; and L-valine, 0.18%. A strict requirement for phenylalanine could not be demonstrated with this diet. Compared to development on a wheat germ diet and the standard 15 amino acid diet, the growth rates were slower and the pupae were smaller on a diet in which all of the essential amino acids in a 15 amino acid mixture were at their minimal levels. © 1979 Entomological Society of America.