With increase in consumption of crude oil and decrease in production of light and medium oils the need for production of heavy oils (API<20) is more than ever before. Production and processing of heavy oils require accurate knowledge of physical and thermodynamic properties which usually are not available. One of the most important properties in calculations related to phase behavior and separation processes is vapor pressure. In this work existing data on vapor pressure of pure hydrocarbons in the range of C1 to C28 included in the DIPPR data bank have been used to develop a new method based on molar refraction for estimation of vapor pressure of heavy hydrocarbons. The advantage of proposed method over exisiting methods such as (Lee-Kesler, Ambrose or Riedel) is that when used for heavy hydrocarbons accurate values of input parameter can be obtained through available data. In fact molar refraction can be accurately estimated and it has a linear relationship with carbon number while accurate estimation of acentric factor for such heavy compounds is not possible. Proposed method was evaluated with data available in the literature on vapor pressure of pure hydrocarbons in the range C30 to C100 over a wide range of temperature in which were not used in the development of the method. Comparison with other existing methods shows a significant improvement for prediction of vapor pressure of heavy compounds. While existing methods estimate vapor pressure with errors in the range of 30-40%, the proposed method estimates vapor pressure of heavy hydrocarbons with errors in the range of 5-10% which is within the range of uncertainty for the experimental data. When the proposed method is applied to heavy petroleum fractions similar errors are obtained.