Characterization of leaky faults in vadose zones of large thickness is very important for engineering problems such as high-level nuclear waste disposal. This paper presents analytical solutions for air flow in faulted vadose zones of large or small thicknesses. The focus is on those sites where the fault zone is more permeable than its adjacent rock matrix. On the basis of the assumptions of a two-dimensional air flow in the matrix and a one-dimensional air flow in the fault zone, analytical solutions are presented for a sinusoidal atmospheric pressure variation. A procedure is then provided for extending the application of the solutions to an arbitrary atmospheric pressure variation. The solutions can help determine air permeability of leaky faults in the vadose zone. ¿ 1999 American Geophysical Union