Current and emerging bone active pharmacologic agents are capable of producing substantial gains in bone mass. However, nutrition must be adequate if this potential is to be realized. Calcium and vitamin D supplementation, for example, have both been demonstrated to augment substantially the skeletal response to estrogen therapy in postmenopausal women. The bisphosphonates and selective estrogen receptor modulator (SERMs) have all been tested only in the context of supplemental calcium and vitamin D. Therefore, it cannot be assumed that these bone active agents would be effective in the absence of these nutrients. Adequate protein intake has also been demonstrated to protect bone mass in the elderly and to improve recovery from osteoporotic fractures. Phosphorus intake, less extensively studied, may be more important than currently recognized, particularly in elderly individuals living alone, eating little meat, and receiving anti-osteoporosis treatment agents.