Nitric oxide is a ubiquitous estrogen regulated signaling molecule which has been implicated in the regulation of bone maturation and remodeling. To better understand the role that bone cell secreted nitric oxide plays in ovariectomy-induced modifications of bone turnover, we examined the expression of eNOS in bone cells and bone progenitor cells at regular intervals up to 10 weeks after acute estrogen deprivation. Ovariectomy led to an anticipated initial decline in bone cell eNOS production but surprisingly, 17 days after ovariectomy eNOS expression by bone and marrow stromal cells dramatically rebounded, and was maintained at high levels for at least 10 weeks after surgery. We examined the long term consequences of eNOS in the process of ovariectomy induced bone loss by prospectively analyzing bone mineral density in WT and eNOS(-/-) mice for 10 weeks after ovariectomy. Ovariectomized eNOS(-/-) mice were observed to undergo an exaggerated state of estrogen deficiency induced bone remodeling compared with wild-type controls, suggesting that eNOS may act to mitigate this process. Furthermore, we found that while bone formation in estrogen replete wild-type mice slowed between 14 and 20 weeks of age, eNOS knock out mice continued to accrue basal bone mass at a high rate, and showed no sign of entering a remodeling stage. Our data suggest that eNOS may play an important role in limiting ovariectomy induced bone remodeling, as well as regulating the transition from basal modeling to remodeling.