The problem of fault diagnosis with communication constraints is considered. Most approaches to fault diagnosis have been focused on detecting and isolating a fault under cost constraints such as eco-nomic factors and computational time. But in some systems, such as remote monitoring (e.g., satellite, sensor field) systems, there is a communication constraint between the system being monitored and the monitoring facility. In such circumstances it is desirable to isolate the faulty component with as few interactions as possible. The key consideration is that multiple tests are chosen at each stage in such a way that the tests within the chosen group complement each other. To this end we propose two algorithms for fault diagnosis under communications constraints. Their performances are analyzed in terms of the average number of testing stages as well as in terms of the required computational complexity.