A radio frequency identifier (RFID) system consists of inexpensive, uniquely identifiable tags that are mounted on physical objects, and readers that track these tags (and hence these physical objects) through RF communication. For many performance measures in large-scale RFID systems, the set of tags to be monitored needs to be properly balanced among all readers. In this paper we, therefore, address this load balancing problem for readers — how should a given set of tags be assigned to readers such that the cost for monitoring tags across the different readers is balanced, while guaranteeing that each tag is monitored by at least one reader. We first present centralized solutions to two different variants of this load balancing problem: (i) min-max cost assignment (MCA), and (ii) min-max tag-count assignment (MTA). We show that MCA, the generalized variant of the load balancing problem, is NP-hard and hence present a 2-approximation algorithm for it. We next present an optima...