Experimental and analytical studies of condensation heat transfer were performed for pure, binary and ternary mixtures of HFC32, HFC125 and HFC134a. These heat transfer coefficients were measured inside a horizontal smooth tube 5.8mm ID and 8m long. The refrigerant mixture in the test section was cooled by water flowing through an annulus around the tube. The refrigerant temperature was 40°C and the mass flux was varied between 150 and 400 kg/m²s for all the experiments. The heat transfer conefficients for nonazeotropic binary and ternary mixtures was about 20% lower than that for HFC134a at low mass flux conditions. A new predictive model for condensation heat transfer of multicomponent mixtures is proposed, in which the heat transfer deterioration due to the mass transfer effect is taken into account both in forced-convection condensation and in free-convection condensation. The predicted results are in good agreement with the experimental ones.