Abstract: What is provided is an apparatus designated as a thermo-roto mixer which would provide a blood specimen mixer portion, comprising a plurality of test tube cradles for housing the test tubes containing blood, so that in the closed position, the test tubes are housed within the cradles within the mixing portion at a desired temperature. The mixing portion is fastened to a shaft supporting the test tube holder assembly, the shafts maintaining the assembly in an overall main frame. The assembly is rotated by the use of a motor pulley assembly, to impart general rotation on the test tube holder assembly.