A novel tri-band bandstop filter (TBBSF) is presented, which has a few special features, such as adjustable bandstop frequencies, compact size, low insertion loss, and sharp rejection. To validate the proposed design, a TBBSF operating at 1.2 GHz, 1.5 GHz, and 2.2 GHz is designed and simulated, the rejection level of more than 40 dB is achieved at the designated bandstop frequencies.