A narrow-bandwidth dual-band (DB) band-pass filter (BPF) with λg/2 open stubs constructed using composite right/left-handed (CRLH) metamaterial transmission lines (TLs) is presented. A conventional narrow BPF with λg/2 open stubs is first designed using series λg/2 open stubs and λg/4 TLs. Then, a DB filter can then be easily implemented by replacing the microstrip lines with the CRLH-TL unit cells. The DB BPF using the CRLH-TL unit cell is experimentally demonstrated at dual-operating frequencies of 5.8 and 10.02 GHz. The experimental results are in good agreement with the simulation results. The DB BPF shows 11 and 13% pass bandwidth at the center frequencies of 5.8 and 10.02 GHz, respectively. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1887–1890, 2013