Here we report that bone morphogenetic proteins 2 and 3 (BMP‐2 and BMP‐3) induced marked expression of c‐fosmRNA in a biphasic manner, i.e. the late phase (48 to 60 h) as well as the immediate‐early phase (0.5 h), in murine osteoblastic MC3T3‐El cells in vitro. The BMP‐induced late phase c‐fosgene expression was temporally associated with the onset of marked expression of the genes for osteocalcin and alkaline phosphatase, differentiation markers of mature osteoblasts. In contrast, none of TGF‐β1, 10% FBS, IGF‐I and IGF‐II, which induced only the immediate‐early c‐fosmRNA expression, stimulated the expression of osteocalcin and alkaline phosphatase genes. These data suggest that in osteoblasts BMP‐2 and BMP‐3 induce the late phase expression of c‐fos, which may play a role in transcriptional activation of the genes involved in differentiation of osteoblasts.