CR-39 plastic nuclear track detector has been used In range determination of alpha particles . A set of experiments was carried out for studying alpha energy and track diameter relationships. This work was done under the optimum conditions of CR-39 etching in 6.25 N NaOH at 70 C for various etching times. Determination of alpha range in CR-39 recorders was studied at different energy values using the overetched track profile technique . Data are discussed within the framework of track formation theory in plastic foils, comparison between experimental and theoretical values of alpha range is included.