This paper investigates the conditions for existence and the characterization of fixed modes in decentralized multivariable control systems employing local controllers. It is shown that for scalar local controllers in the diagonal control structure, the necessary and sufficient condition for a system polo ats= λ to be a fixed mode is thats= λ be a transmission zero of all subsystems formed by selecting the same inputs and outputs of the system. The results are applied to scalar controllers in any arbitrary control structure and also to non-scalar local controllers and similar conditions are obtained. Examples are discussed for illustration.