It is shown that the three pure-component parameters in the Sanchez-Lacombe equation of state can be determined from the critical temperature, critical pressure, and acentric factor. Vapor pressures from the equation have accuracy comparable to that obtained with the original Soave-Redlich-Kwong equation and Peng-Robinson equation, even without introducing any temperature dependence in the parameters. If temperature dependence is added to the Sanchez-Lacombe epsilon energy parameter, the accuracy in the vapor pressures can be improved.