An experimental setup was designed and fabricated to test the flow boiling heat transfer performance of microfin tubes. Five microfin tubes were tested with pure refrigerants. Two tubes were selected for further testing with binary and ternary refrigerant mixtures. This paper reports the data for these two microfin tubes employing R22, R410A (mixture of 50% by weight of R32 and 50% of R125) and R407C (ternary mixture of 23 wt. % R32, 25 wt. % R125, and 52 wt. % R134a). A correlation scheme is presented for the heat transfer coefficient of mixtures in microfin tubes. In general, it is observed that the heat transfer performance of binary mixture R410A in microfin tubes is similar to pure R22; however, the performance of the ternary mixture R407C is lower than that with pure R22.