Background: RecQ helicases are a family of proteins that regulate genome stability. Of the 5 human helicases, BLM, WRN and RECQL4 are associated with familial cancer predisposition and aging syndromes. A substantial number of patients with Rothmund-Thomson Syndrome (RTS), attributed to RECQL4 mutations, have skeletal abnormalities and an increased risk of developing osteosarcomas. However, it is not known how RECQL4 affects bone development and cancer. In this study, we have analysed the effects of Recql4 loss in murine osteoblasts. Methods: Primary long-bone osteoblastic cells from C57BL/6 mice and an osteoblastic cell line (Kusa4b10) were transduced with shRNA against Recql4 and shRNA-Luciferase as a control. Mice bearing a floxed Recql4 allele were bred with a range of Cre mice to investigate the role of Recql4 in vivo in normal bone and osteosarcoma formation. Results: The knockdown of RECQL4 by shRNA in vitro was confirmed by immunoblotting. RECQL4 depleted cells displayed dramatically reduced cell proliferation and showed a decrease in Sca-1 expression, a marker of proliferative precursor cells. In vivo, Recql4 deletion in osteoblasts resulted in mice that were smaller, had decreased weight and shorter bone lengths than their wildtype counterparts. mCT analysis also demonstrated a reduction in trabecular bone volume and cortical thickness. Conclusion: The loss of Recql4 in proliferating osteoblastic cells results in decreased cell proliferation. Future experiments will explore the role of Recql4 in cancer through the use of engineered models of osteosarcoma.