The effects of bee pollen extract on bone components in the femoral-diaphyseal (cortical bone) and -metaphyseal (trabecular bone) tissues of rats in vitro and in vivo were investigated. Bone tissues were cultured for 48 hr in serum-free Dulbecco's modified Eagle's medium containing either vehicle or water- or ethanol-solubilized extracts (10, 100, or 1000 μ g/ml of medium) obtained from the bee pollen of Cistus ladaniferus . Calcium content in the femoral-diaphyseal or -metaphyseal tissues was significantly increased in the presence of water-solubilized extract (100 or 1000 μ g/ml) and ethanol-solubilized extract (1000 μ g/ml). An increase was also observed in the presence of water-solubilized extract (100 μ g/ml) obtained from Fagopyrum esculentum , Camellia sinesis , or Brassica napus L . Alkaline phosphatase activity and DNA content in the femoral-diaphyseal or -metaphyseal tissues in vitro were significantly increased in the presence of water-solubilized extract (100 or 1000 μ g/ml) obtained from the bee pollen. The effects of the bee pollen extract (100 μ g/ml) in increasing bone components were completely inhibited in the presence of cycloheximide (10^-6 M), an inhibitor of protein synthesis, in vitro . Moreover, the calcium content and alkaline phosphatase activity in the femoral-diaphyseal or -metaphyseal tissues were significantly increased by the oral administration of water-solubilized extracts (5 or 10 mg/100 g body weight) obtained from the bee pollen of Cistus ladaniferus once daily for 7 days. The DNA content in the diaphyseal or metaphyseal tissues was significantly increased by the oral administration of water-solubilized extract (10 mg/100 g) of bee pollen cistus. The dose of 1.0 mg/100 g caused a significant increase in the diaphyseal and metaphyseal alkaline phosphatase activity or the metaphyseal DNA content in vivo . This study demonstrates that the extract of bee pollen has an anabolic effect on bone components in rats in vitro and in vivo .