Mechanisms which trigger bone modeling/remodeling in response to changes in the mechanical environment are still unclear. In a three part study, effects of loading on osteoblast function were investigated using a three dimensional (3-D) ceWpolymer model. The 3-D model has advantages of cell culture while maintaining the natural matrix architecture of bone. Such celVpolymer constructs have been shown to form bone in vitro. Osteoblasts in 3-D ceWpolymer constructs were cyclically loaded (5% ). After five days, compressed constructs decreased in alkaline phosphatase activity, a marker of osteoblast maturation. After three weeks, loaded constructs showed lower alkaline phosphatase activity but higher RNA level of L-type calcium channels, involved in calcium signaling cascades. No difference was detected after twelve weeks. Results suggest osteoblasts sensed loading and altered functional activities in response. Use of the 3-D model to study other osteoblast functions under mechanical loading may increase understanding of regulated functional adaptation by bone.