Abstract This study analyzes the impacts of permeability anisotropy and pressure interference on CBM (coalbed methane) performance with emphasis on identifying any unique feature that might allow us to diagnose permeability or flow anisotropy. Simulation results indicated that a "dual-peak" behavior in the gas rates arises if drainage boundaries are not influenced at the same time. Examples include anisotropic permeability in a square area and isotropic permeability in a rectangular area. The dual-peak behavior does not present if the drainage area is scaled according to the permeability anisotropy (the "square-root rule"). As noted in the literature, well interference has positive impact by accelerating gas production. The "dual-peak" behavior may potentially provide a methodology to diagnose permeability anisotropy and drainage shape from CBM performance. Further research, however, is needed.