Objective: To study the effects of parathyroid hormone(PTH) on the calcification characters of cultured human dental papilla mesenchymal(DPM) cells.Methods: DPM cells were cultured up to 35 days in two groups. The control group was cultured in DMEM supplemented with 15% FCS,50 ?g/ml ascorbic acid and 10 mmol/L ?-glycerophosphate. The cells in experimental group were cultured in above mentionned medium containing 33.3 nmol/L of PTH. The medium was changed every 3 or 4 days. Osteocalcin secretion of the cells was measured by radioimmunoassay.Results: Addition of TPH in medium caused a significant increase of osteocalcin secretion from 21 to 35 days culture (P