Two-phase flow pattern data have been obtained experimentally for R-407C flowing inside 12 mm bore sight glasses, which were located at the outlets of 3 m long, plain bore copper tube heat transfer test sections. The tests covered nominal mass velocities of 100, 200 and 300 kg/m2s, vapor qualities from 5-95%, and a wide range of heat fluxes, all taken at a fixed inlet saturation pressure of 6.45 bar to the evaporator test section. The flow pattern data were compared to the newly developed two-phase frow pattern map of Kattan, Thome and Favrat (1997) and Kattan (1996). The flow pattern map covers both adiabatic flows and diabatic flows for evaporating refrigerants, including the prediction of the onset of dryout at the top of the tube in the annular flow regime as a function of heat flux. This flow pattern map, formerly developed from a database for R-123, R-134a, R-502, R- 402A and R-404A, accurately predicted the new flow pattern data and the onset of dryout of R-407C without modification.