Isothermal vapor-liquid equilibria for the three binary systems (1-chloro-1,1-difluoroethane + hydrogen fluoride, 1,1-dichloro-1-fluoroethane + hydrogen fluoride, and chlorodinuoromethane + hydrogen fluoride) have been measured. The experimental data for the binary systems are correlated with the NRTL equation with the vapor-phase association model for the mixtures containing hydrogen nuoride, and the relevant parameters are presented. All of the systems form minimum boiling heterogeneous azeotropes.