Repairing of the cracks by fiber metal laminates (FMLs) was first done by some aeronautical laboratories in early 1970s. In this study, experimental investigations w ere done on the effect of repairing the center-cracked aluminum pla tes using the FML patches. The repairing processes were conducted to characterize the response of the repaired structures to tensile test s. The composite patches were made of one aluminum layer and two woven glass- epoxy composite layers. Three different crack lengt hs in three crack angles and different patch lay-ups were examined. I t was observed for the lengthen cracks, the effect of increasing t he crack angle on ultimate tensile load in the structure was increase . It was indicated that the situation of metal layer in the FML patche s had an important effect on the tensile response of the tested specim ens. It was found when the aluminum layer is farther, the ultimate te nsile load has the highest amount. Keywords—Crack, Composite patch repair, Fiber metal laminate (FML), Patch Lay-up, Repair surface, Ultimate load I. INTRODUCTION IBER-METAL LAMINATES (FMLS) are hybrid structures based on thin sheets of metal alloy and plies of fi ber- reinforced polymeric materials. These hybrid materi al systems combine the excellent specific strength and stiffne ss, and fatigue properties of composites and the machinabil ity and toughness of metals (1) They were initially develop ed at the National Aerospace Laboratory in Nether-lands, afte r fatigue studies on the centre wings of a Fokker F-27 showed that bonded metal laminates presented promising fatigue properties (2). Subsequent enhancement of their mechanical properties at the Technological Delft University resulted into co mmercially available FMLs under the trade name of ARALL (aramid fibre/aluminium) and GLARE (glass fibre/aluminium) (2).