A group-contribution method has been developed for predicting the enthalpy of vaporization for organic liquids. The parameters for 39 organic groups are derived from 3396 experimental enthalpy of vaporization data on 509 organic compounds. The various group constants are presented as three-constant Graue et al. equation and can be used to estimate the enthalpy of vaporization for organic liquids up to 100 kJ mol(-1). With this method, enthalpies of vaporization have been calculated for 509 organic compounds, and when compared with experimental data, this method produces an average absolute error of 0.74 kJ mol(-1) with a standard deviation of 1.08 kJ mol(-1). The overall average absolute percentage deviation is 2.5%. The proposed method is relatively easy to use. The critical temperatures required for this method have been provided. Based on the same database, 14 correlation equations were studied and six other prediction methods in the literature were compared.