A new, simple, accurate three-parameter enthalpy-of-vaporization equation is constructed consistent with the renormalization-group theory of critical phenomena. The proposed equation is valid over the entire range from the triple point to the critical point for various pure compounds and reproduces data within the experimental accuracy. Since the correct near-critical behavior is built in, the new equation is often better than existing enthalpy-of-vaporization equations in that it can be used to not only accurately correlate but also effectively extrapolate from the usual range in which data are available both to the critical point and to the triple point. Fitted parameters are given for 30 pure substances. The result is compared with experimental data and previous equations.