To investigate the telomerase activity in mesenchymal stem cells (hMSCs) from human bone marrow after their in vitro committed differentiation into adipocytes and cryopreservation.hMSCs were isolated from human bone marrow. The isolated hMSCs were induced to differentiate into adipocytes in vitro or cryopreserved. TRAP assay (telomerase repeat amplification protocol assay) was employed to detect telomerase activity in those hMSCs.Telomerase activity (RTA) in hMSCs (n=19) was (1.46 +/-0.67)%, while that in hMSCs-derived adipocytes (n=3) was (11.80 +/-2.52)% (P<0.001). RTA of hMSCs-passage 1.3 (n=10) was (1.46+/-0.83)%, and that of hMSCs-passage 4-7(n=9) was (1.46 +/-0.47)% (P=0.99). Cryopreservation did not affect the telomerase activity in hMSCs, RTA of fresh hMSCs (n=13) was (1.41 +/-0.44)%, RTA of frozen hMSCs (n=6) was (1.57 +/-1.07)% (P=0.64).hMSCs are telomerase-negative, but telomerase activity in hMSCs-derived adipocytes is upregulated.