In this letter, we propose an eigen domain interference rejection combining (E-IRC) algorithm to suppress the narrowband interference (NBI). The proposed E-IRC algorithm explores the difference between the time domain autocorrelation matrices of the NBI and the desired signal and implements the IRC in the eigen domain. Compared with the traditional IRC, which rejects the interference in the spatial domain, the proposed E-IRC algorithm exploits the characteristics of the received signal in both the time and spatial domain to suppress the NBI and thus yields better performance. Simulation results are presented to demonstrate the advantage of the proposed algorithm.