Abstract: This paper presents a comprehensive review of millimeter-wave (mm-wave) passive bandpass filters (BPFs). A detailed discussion is provided on different topologies and architectures, performance comparison, design challenges, and process technologies. Passive BPFs offer the advantages of high operating frequency, good linearity, low noise figure (NF), and no power dissipation. Careful consideration of available process technologies is required for the implementation of high performance mm-wave circuits. Gallium arsenide (GaAs) and indium phosphide (InP) (group III-V) processes provide high cutoff frequencies (fT), good noise performance, and high quality on-chip passives. Complementary metal oxide semiconductor (CMOS) process has the prominent advantages of low cost, a high degree of integration, and high reliability, while silicon germanium bipolar CMOS (SiGe BiCMOS) process demonstrates high fT, a high level of integration, and better noise and power performance.