In this study, an optimization methodology is presented to obtain the uniform thermal conditions over the design body (DB) surfaces. The DB has an asymmetrical and irregular shape that is placed inside a 3-D radiant enclosure equipped with heaters on its top wall. The Monte Carlo ray tracing (MCRT) method and genetic algorithm (GA) are employed to find the optimal temperatures of the heaters and the best location of the DB inside the enclosure. The radiative heat transfer problem is solved on the basis of the MCRT method to calculate heat fluxes on the DB surfaces. The GA is used to minimize the objective function defined based on the calculated and desired heat fluxes. The results indicate that thermal conditions on the DB surfaces are greatly influenced by the location of the DB and temperatures of the heaters. It is concluded that the introduced method is very capable of achieving the uniform thermal conditions on the DB surfaces by finding the optimal values for temperatures of the heaters and the best location for the DB inside the radiant enclosure.