19 randomized controlled studies, with a total of 6759 patients, were included in this meta-analysis investigating the role of vitamin K2 in postmenopausal women with osteoporosis. The purpose of the study was to compare bone mineral density, and incidence of fractures, as well as adverse events in patients taking oral vitamin K2 supplements and those not. Results indicated a significant improvement in vertebral bone mineral density in those taking vitamin K2 when compared to the control group. Incidence of fractures was similar between groups, although exclusion of a study during sensitivity analysis revealed that vitamin K2 offered significant protection in this regard for women with osteoporosis. There were more adverse events in the K2 group than in the control group.