A filter cloth for air bags comprises a woven synthetic fibre fabric comprising a ground weave segment of a single plain or single twill construction, and several high-gas-permeability woven segments formed in the ground weave at a constant distribution density, exhibiting a higher air permeability than that of the ground weave and being a mock leno weave having pinhole-like openings, a duble plain weave, or a double twill weave. IPC D03D.