Neonatal female and male rats of the Sprague-Dawley strain were injected subcutaneously with a daily dose of MSG (2.2–4.2 mg/g body wt.) beginning on the 2nd day of life. The rats were autopsied at 40 and 110 days of age. At 40 days of age, the body weight and nasoanal lengths were significantly reduced in the MSG-treated rats. At 110 days, the body lengths of MSG-treated rats were approximately 10–12% shorter than those of control rats, and calculation of the ‘Lee’ index indicated a significant increase in carcass fat. Food consumption studies, carried out at 75 days of age, showed a significant hypophagia in some MSG-treated rats. Upon autopsy at 40 days of age, the absolute weights of the thyroid and adrenal glands of both sexes were significantly decreased from those of control rats; but when corrected for body weight, these differences were marginal. At 110 days, the absolute weights of the adrenal and thyroid glands of both sexes were significantly reduced from their respective control levels. Gonadal weights of MSG-treated rats were significantly reduced at 40 and 110 days of age. Size and weight of the anterior pituitary glands of both male and female MSG-treated rats were significantly reduced from control values. There was a marked decrease in growth hormone and luteinizing hormone content in the anterior pituitaries of male and female MSG-treated rats at 40 days. However, thyrotropin content of the anterior pituitary of MSG-treated male rats did not show any significant change from control levels at 40 days of age.