In this paper, a frequency reconfigurable slot antenna using PIN diodes is proposed. The proposed structure is based on an open-end straight slot line on the bottom layer and a microstrip line input on the top layer. By means of the two PIN diodes and the associated dc bias network, the proposed antenna has the ability to alternatively switch the operating frequency. The proposed antenna is made of FR4 substrate and use commercial PIN diodes. The measured results agree with simulated results, and further verify the design concept. The proposed antenna can be applied in the commercial wireless communication due to its low cost and low profile properties.