In animal models of osteoporosis, the anabolic effects of Sr have been reported in some studies while not in others.5-8 There are several factors which may contribute to the controversy, such as animal age, dose and duration of Sr treatment.9 Another important factor is the intervention timing. For instance, Sr treatment increased trabecular bone volume and bone formation in ovariectomized (OVX) rats when the treatment was initiated on the day after the ovariectomy.5, 6 Our previous studies showed that early Sr treatment increased mineral apposition rate, bone formation rate and osteoblast‐related genes in the long bones in OVX rats6. On the other hand, Sr treatment at similar dose failed to increase trabecular bone volume, bone formation or strength when the treatment was initiated after the establishment of osteopenia in OVX rats.7, 8 In this study, we aim to investigate the effect of Sr treatment intervention timing on bone mechanics in OVX rats, and investigate the possible mechanisms at the tissue, cellular, and molecular levels.