The effects of newly synthesized, reverse transcriptase inhibitors, 3-benzazepines, for their effects on natural killer (NK) cell and blast transformation in human peripheral blood mononuclear cells were investigated. The most effective reverse transcriptase inhibitors were KF1, KF2 and KF3, which primarily suppressed immunological functions. Besides the inhibition of T cell proliferation, the benzazepines also show inhibitory effect on NK cell functions, in particularly, against large granular lymphocytes and monocytes. The B lymphocytes and Fc mediated killer functions were less inhibited.