The State Estimation (SE) constitutes the main core of the online security analysis, such that the development of suitable strategies to improve state estimators is one of the main aims in the transition toward smart control centers and transmission systems. This paper focuses on an alternative method for multiarea state estimation (MASE) based on Optimality Condition Decomposition (OCD). The state estimation problem is addressed through a decentralized optimization scheme with minimum information exchange among subsystems. The proposed method is applied to an equivalent of the Mexican power grid of 190-buses, which has been split into two and three subsystems. Results indicate that the proposed strategy is a reliable alternative.