The paper deals with design principles of relay and variable structure observers for multi-input multioutput systems with time-lag. We thus have suggested design methods and synthesis of state observes for multi-input multi-output (MIMO) systems with rime lag. ln the case of relay observer high amplification factor is used for the model of the observer. in both cases, namely, relay observer and variable-structure observer, the sliding modes are imposed to the system deliberately. Most importantly, for the both state observers considered the error equation of motion is proved to be globally asymptotically stable.