A robust Nyquist array analysis for MIMO systems is proposed based on uncertainty descriptions obtained from system identification. Two types of statistical-based uncertainty error bounds for the frequency response are obtained: element bounds and column bounds. Gershgorin's theorern and the concepts of diagonal dominance and Gershgorin bands are extended to include model uncertainty. Robust stability theorems are developed based on ellipsoidal uncertainty descriptions obtained from System identification. An example is given to illustrate the robust Nyquist array analysis.