Polyethylene waxes are manufactured from low molecular weight, high-density raw materials, designed to give the particular performance characteristics required by industry. Waxes are broadly divided into several well established groups. These include paraffin waxes (normally obtained from petroleum oil lubricating distillates), microcrystalline wax (usually obtained from residual lubricating oil fractions), soft waxes which include isoparaffinic and naphthenic waxes usually obtained during the deoiling of paraffin waxes, and the so-called high melting point waxes normally obtained by fractionating microcrystalline wax. Polyethylenes employed have had average molecular weights in the range of about 1500 to about 20,000. Certain combinations of polyethylenes have been shown to have certain advantages. The combinations have included a mixture of low and high average molecular weight polyethylenes in order to obtain an optimum combination of physical properties in the wax compositions. In this research, Effect of molecular weight distribution (MWD) on the viscoelastic behavior and thermal properties of two type of HDPE wax (wax of BL3 and EX3 grades), were investigated. The MWD of the samples were studied by Gel permeation chromatography (GPC). Dynamic- Mechanical Analysis (DMA) was used to study the elastic modulus. Thermal properties of wax samples were evaluated by differential scanning calorimetry (DSC). The GPC results have shown that the both samples had broad MWD. Curve of BL3 wax was broader than EX3 wax but, the curve of EX3 wax, located in the higher range of molecular weight than the BL3 wax. The DSC results have shown that sample of EX3 wax had higher Tg and melting temperature range than the other sample. DMA curves of samples showed the same results for the Tg of samples. DMA results also showed that the EX3 wax had higher elastic modulus than the BL3 wax. Results showed that sample with the higher range MWD, had better viscoelastic behavior and thermal properties.