Objective To investigate the variation in lymphocyte steroid sensitivity (LSS) on activation and secretion in vitro among healthy human volunteers from Xuzhou,China.?Methods Peripheral blood lymphocytes (PBLs) from 120 young volanteers of Han nationality, were used as the target cells. They were treated with phytohemagglutinin (PHA) and dexamethasone (Dex) at concentrations of 10~-8 to 10~-6 mol/L.After 72 h of cultivation, the interleukin-2 (IL-2) level was determined by ELISA,the expression of CD3 and CD25 by flow cytometry. All of the assessments were repeated three months later. Maximal percentage inhibition (I_~max ) was defined as the maximal percentage inhibition either of secretion or activation achieved at different concentrations of Dex. Taking 50% as the set point,the individuals who failed to achieve more than 50% inhibition were considered as steroid-resistant (SR), and those whose inhibition exceeded 50% as steroid-sensitive (SS).?Results Analysed results showed there were 80 SS and 23 SR.Dex of different concentrations inhibited the activation and secretion in a dose-dependent manner (P<0.05), while in the SR group,no such findings were noticed.The I_~max values,both of activation and secretion,might deviate widely between individuals in the same SS group, but remained stable in a given individuals over time.?Conclusion I_~max is a stable parameter responsible for LSS in vitro.The fault of LSS may be widely present in healthy people, as up to 20.9% of healthy Han youth in Xuzhou were found to be SR.It is believed that hereditary background may play an important role in variation of LSS.