A total of 123 female rats were used to determine the influence of blinding and anosmia, either alone or in combination, on sexual maturation, growth of the reproductive organs, and the activity of the pineal gland. Whereas blinding or anosmia alone caused a statistically insignificant delay in the onset of puberty, when the operations were combined, sexual development and growth of the reproductive organs were severely retarded. The inhibition of sexual maturation in blinded, anosmic rats was prevented if the pineal gland had been removed. The level of the pineal enzyme, hydroxyindole-O-methyltransferase, was exaggerated by blinding, but not by anosmia. it is concluded that blinding inhibited sexual development by acting through the pineal; it is further proposed that anosmia, although not acting through the pineal, rendered the site of action of the pineal substance highly sensitive to the antigonadotropic influence.