This paper is concerned with the input-output stability of non-linear multivariable feedback systems. The class of feedback systems considered consists of a linear time invariant element in the feedforward path and a non-linear element in the feedback path ; although differing feedback configurations may be considered by use of suitable transformations. By expressing the linear time invariant part as the sum of a normal operator and the difference, graphical Nyquist-type conditions are shown to ensure theL2stability of the non-linear multivariable feedback system. The frequency domain criteria present are of the circle type and may be viewed as the multivariable counterparts of the scalar multiplier results of Cho and Narendra (1968), Zames and Falb (1968).