The fatigue behaviour of acrylic sheet specimens containing reinforcers were investigated. Three different kinds of reinforcers namely, stainless steel, aluminum reinforcer and three flex wire were used as strengtheners in acrylic resin sheets. The tests were carried out on alternating bending fatigue testing machine specially designed to test sheet specimens. By applying static and dynamic bending moments of any desired magnitude within the permissible capacity likits of the machine the fatigue lives of the specimens were determined. Experimental results showed that stainless steel strengtheners had a significant positive effect on the fatigue behaviour of acrylic resin.