Hypogonadism and oxidative stress increase the risk for developing osteoporosis. The objective of this research was to evaluate the efficacy of drinking grapefruit juice on bone quality in orchidectomized (ORX) and non-ORX rats. Fifty-six 90-day-old male Sprague-Dawley rats were equally divided into four groups--non-ORX rats (sham), sham + grapefruit juice, ORX, and ORX + grapefruit juice--and treated for 60 days. Thereafter, all rats were sacrificed to determine the plasma antioxidant status, insulin-like growth factor I (IGF-I), and indices of bone turnover, bone quality, and calcium and magnesium concentrations in the bone, urine, and feces. Orchidectomy decreased (P < .05) antioxidant status, bone quality, and bone mineral contents and increased (P < .05) indices of bone turnover, urinary deoxypridinoline, calcium, and magnesium, and fecal calcium excretions. In contrast to the ORX group, ORX rats that drank grapefruit juice had an increase (P < .05) in antioxidant status, bone density, and bone mineral contents, delayed femoral fracture, and slowed down (P < .05) bone turnover rate and tended to have a decrease (P = .08) in urinary deoxypridinoline. In sham-treated animals, drinking grapefruit juice increased (P < .05) bone density and tended to increase the femoral strength. The concentration of IGF-I in the plasma was not affected across treatments. In conclusion, drinking grapefruit juice positively affected bone quality by enhancing bone mineral deposition in ORX rats and by improving bone density in non-ORX rats via an undefined mechanism.