Abstract-A highly miniaturized simplified composite right/left handed (SCRLH) mushroom zeroth-order resonator (MZOR) is proposed for bandpass filter (BPF) design. By introducing the Uslot etched around the metallic via, more flexible selection of the shunt inductance value can be achieved compared with the original one. As the length of U -slot increased, zeroth-order resonant frequency of the MZOR decreased, even 88% size reduction can be achieved. Finally, a bandpass filter based on the proposed MZOR is designed, fabricated and measured. The simulated and measured results are presented and good agreement is obtained.