Gougerotin, together with blasticidin S and puromycin, enhanced the T factor-dependent enzymatic binding of phenylalanyl-tRNA to ribosomes. But, they have no effect on the nonenzymatic binding of phenylalanyl-tRNA to ribosomes or on the GTP binding activity of T factor.This gougerotin-dependent stimulation of the enzymatic binding of phenylalanyl-tRNA to ribosomes seems to be responsible for the increment of the number of poly-phenylalanine peptides produced in the presence of gougerotin. © 1969 BY THE JOURNAL OF BIOCHEMISTRY.