A new method of evaluation of beta-receptor's activity on the surface of human T-lymphocytes has been proposed based on the radioligand method. Optimal conditions for evaluation of specific binding to β2-adrenoceptors of 0.5 fmol ligand per 1 million cells using [125I] -cyanopindolol were found. The possibility of using β2-adrenoceptor's activity assessment in clinical settings was demonstrated on human T-lymphocytes.