This study examined the influence of adolescent development and pubertal changes in gonadal function on the development of norepinephrine (NE) turnover in the hypothalamus and cerebral cortex of rats from late juvenile to young adult ages. In one study, NE utilization was estimated in intact male rats and in male rats castrated at 14 days of age. NE levels were measured 15, 30, 45, 60, 120, and 240 min after inhibition of catecholamine synthesis at 28, 42, and 70 days of age. In a second study, male rats were made precocious by chronic testosterone exposure over days 14–28 and on the 28th day NE utilization was measured in both the hypothalamus and cerebral cortex. Turnover rates were calculated based on steady-state kinetics. The results indicate that in vivo NE levels and turnover rates in both the hypothalamus and cortex significantly increase from a late juvenile age to adulthood. However, when NE levels measured after synthesis inhibition were expressed as a percentage of the mean basal values, there was a significant effect of age only in the hypothalamus. Hence, the age-related increases in hypothalamic NE turnover appear to reflect age-related changes in NE utilization, whereas the increases in cortical turnover rates reflect the increasing basal levels and not age-related changes in NE utilization. During mid-puberty (42 days), NE utilization in the hypothalamus was markedly different from that observed in this region at either 28 or 70 days. At 28 and 70 days, NE levels decreased to 50% of basal levels by 4 h following synthesis inhibition. At 42 days, NE levels decreased slightly over the first 45 min to 11% of basal levels but by 60 min reached 50% of basal levels. Juvenile gonadectomy had no significant effect on turnover rates at any of the ages. Chronic exposure to testosterone propionate accelerated gonadal development and increased plasma testosterone levels but did not affect NE turnover rates in either the hypothalamus or the cortex. These results indicate that function within the hypothalamic noradrenergic system, therefore, changes over adolescent development, but the change is not influenced by gonadal hormones. The differences seen in NE utilization over adolescence may reflect changing physiologic function within the NE cells or changes in synaptic input onto the NE terminals in the hypothalamus.