Wnt signaling pathway components have been shown to be involved in bone biology since mutations in the LRP5 gene proved to cause osteoporosis-pseudoglioma syndrome and high bone mass trait. Genome wide association studies have indicated that single nucleotide polymorphisms of various components in Wnt signaling pathways are associated with bone mineral density and risk for low-trauma fracture. Mouse genetic studies have demonstrated that multiple components in Wnt signaling pathways play significant roles in skeletal development and bone mass maintenance. Here we review several components in Wnt signaling pathways with their association with bone mineral density in humans.