The effect of bee pollen extract on osteoblastic MC3T3-E1 cells was investigated. The water-solubilized extracts, which were obtained from the bee pollen of Cistus ladaniferus, was purified using the membrane fractionation method with molecular weight (MW) less than 1000. Osteoblastic cells were cultured for 72 hr in a medium containing either vehicle or cistus extract of less than MW 1000 (10, 25, or 50 μg/ml of medium) in the presence of 10% fetal bovine serum (FBS). The proliferation of osteoblastic cells was significantly enhanced in the presence of cistus extract (25 or 50 μg/ml). The stimulatory effect of cistus extract on cell proliferation was also observed when the cells with subconfluency were cultured for 24 or 72 hr without FBS. Cells with subconfluency were cultured for 24 or 72 hr in a medium containing either vehicle or cistus extract without FBS. DNA content or alkaline phosphatase activity in osteoblastic cells was significantly increased after culture with cistus extract (50 μg/ml) for 24 hr. The effect of 25 μg/ml of cistus extract on these components was seen after culture for 72 hr. This study demonstrates that the cistus extract fraction of less than MW 1000 has anabolic effects in osteoblastic MC3T3-E1 cells which involve in bone formation.