An approximation for the performance analysis of single-server tandem queues with small buffers and generally distributed service times is presented. The approximation is based on the decomposition of the tandem queue into subsystems, the parameters of which are determined by an iterative algorithm. By employing a detailed description of the service process of each subsystem, it proved possible to obtain an accurate approximation of performance characteristics such as throughput and mean sojourn time. The proposed technique significantly outperforms existing methods