Newborn male Wistar rats were treated with nerve growth factor daily by subcutaneous inJection for 2 weeks, and control rats were treated with either cytochrome c or buffered saline. Average body weight of the treated animals was lower than that of the controls during the 2 weeks of treatment, but became simdar to that of the controls thereafter. Tissue levers of norepinephrine were elevated in the brain, adrenal glands, nlesernteric arteries, and vas deferens of the treated animals immediately after the treatment, but became simliar in the three grcalps 2 weeks after tbe terminndon of tbe treatment. Blood pressure and heart tale were measured beginning at 4 weeks of age until 28 becks, when the rats were sacrificed and the mesenteric arteries sampled for morphometric measurements of vessel wall dimensions. Pretreatrnent with nerve growth fac tor did not affect blood pressure, nor heart rate. Stroctural atteration of the three types of mesenteric arteries was also absent in the treated animals. We conclude that even though neonatal treatment of normal Wistar rats with nerve growth factor for 2 weeks induced an elevation of the norepinephrine levels in severat tissues at the end of the treatment period, it was not sufficient to produce hypertension and structural alterations in the blood vessels.