Flow boiling experiments for two new non-azeotropic, three-component refrigerant mixtures (HP80 and HP62) and R-502 have been carried out inside a 12 mm bore, horizontal tube. Local boiling coefficients for HP62 are slightly larger that those for R-502 under the same test conditions while those for HP80 are slightly smaller. The heat transfer performances of the three fluids are accurately predicted by an existing flow boiling correlation modified here to include a nucleate pool boiling mixture equation.