Abstract: Microstrip hairpin resonator filters have found wide applications in microwave planar circuits and microwave integrated circuit (MIC) due to the virtues such as compact structure, low cost, easy fabrication, and easily integrated. They have been investigated by many researchers, but the work usually focused on the design of filters using a specific structure of a hairpin resonator. In this paper, several 3-pole and 4-pole bandpass filters using different hairpin resonators and different coupling schemes are investigated and compared for applications. Some useful conclusions are obtained.