Surface textures commonly found on natural opening-mode fractures (joints) in rock are indicative of cyclic loading. The effect of uniaxial strain cycling on the development of a set of fractures in layered brittle materials was studied using a series of model experiments on polymethyl methacrylate (PMMA) sheets covered with a thin brittle coating. Changes in five geometric parameters, including number of fractures, total length, average length, average spacing, and spatial density, were recorded during each experiment. Two major factors, strain rate and strain magnitude, are also considered under the cycling condition. Three groups of experiments are (1) for different strain magnitudes, (2) for different strain rates with the same total strain, and (3) for increasing strain cycling. It is found that few new fractures appear after a certain number of cycles as old fractures keep getting longer; and the geometric parameters, as functions of cycles, decrease or increase rapidly for the first several cycles and then tend not to change much. A greater strain or strain rate increases propagation velocity and fracture length. The critical value of strain for fracturing can be expressed as a function of cycles, and it decreases with increasing cycles. The fractures with different lengths have different propagation velocities, but all decrease very quickly after the first several cycles. ¿ American Geophysical Union 1992