Osteoporosis is characterised by excess bone fragility resulting from bone loss and altered bone microarchitecture. Bone loss occurring during aging and after menopause in women is known to result from an imbalance between bone formation and resorption. Bone formation is dependent on the commitment of osteoprogenitor cells, the proliferation of pre-osteoblasts, their differentiation into mature osteoblasts synthesising bone matrix and the life-span of mature osteoblasts. Transforming Growth Factor ß (TGFß) and Fibroblast Growth Factors (FGFs) are important factors that promote osteoprogenitor cell proliferation and osteogenesis. Reduced expression of TGFß in bone was found in several animal models of osteopenia. In addition, both FGF and TGFß were found to exert anabolic effects on bone formation in intact animals and to reduce bone loss in experimental models of osteoporosis. Both genetic manipulation of FGF and TGFß or their receptors in mice and bone phenotype associated with FGF receptors and TGFß mutations or polymorphism suggest that TGFß and FGF signalling may contribute to the control of osteogenesis and bone mass in vivo. The determination of molecular mechanisms involved in the anabolic actions of FGF and TGFß in cells of the osteoblastic lineage may lead in the future to the development of new therapeutic strategies aimed at improving bone formation in osteoporotic patients.