ABSTRACT Smart Grid has revolutionized Traditional Grid System by merging bi-directional communication network and information technology. Advanced Metering Infrastructure (AMI) is an integral part of Smart Grid used to measure power consumed and demands at consumer-end. In this article, we propose an efficient and secure cluster-based architecture for AMI in Smart Grid, which fulfills the primary security requirements like confidentiality, authentication and integrity. Analysis shows that the proposed secure architecture for AMI in Smart Grid is efficient in terms of resource utilization