Objective:To examine the roles of follicular helper T(Tfh)cells,serum IL-21 and B cells in the pathogenesis of alcohol abuse non-traumatic osteonecrosis of the femoral head ( NONFH ) .Flow cytometry was used to measure the frequencies of peripheral blood inducible Tfh cells and B cells in alcohol abuse NONFH patients and healthy controls.The disease progression and the extent of femoral head collapse,the serum IL-21 were quantified.Methods: A significantly higher percentages of CD19+B cells(t=3.765,P=0.0005),CD86+CD19+B cells(t=5.506,P<0.0001),and CD95+CD19+B cells(t=4.152,P=0.0002) in patients than those in controls was found.The percentages of CD86+CD19+B cells were positively associated with the index of femoral head collapse in alcohol abuse NONFH(P<0.0001,r=0.536).Results: The frequencies of Tfh cells (t=7.611,P<0.0001),and IL-21+Tfh cells (t=5.281,P<0.0001) were higher than those in controls;The frequencies of Tfh cells were positively associated with the percentages of CD19+B cells(P=0.0002,r=0.455),IL-21+Tfh cells were positively associated with the percentages of CD86+CD19+B cells(P=0.0002,r=0.447).Conclusion: Tfh cells and B cells may participate in the pathogenesis of alcohol abuse NONFH,and increased CD86+CD19+B cells may be associated with the extent of femoral head collapse,the interaction of Tfh cells and B cells may have an im-portant role in pathogenesis of alcohol abuse NONFH.