A compact combination blood cell count and immunoassay apparatus for measuring drawn whole blood specimen includes a load station for receiving the whole blood specimen and a nozzle member that can selectively withdraw whole blood from the blood specimen. A blood cell count section and an immunoassay section are mounted along a unitary path of movement of the nozzle member so that a single nozzle member may be used for transporting the whole blood to the respective blood cell count section and immunoassay section. A controller can automatically direct a transport mechanism to use only the whole blood and to perform various steps of adding dilution liquid and reagents, along with appropriate washing of the nozzle and sample cells to insure an automatic operation. A hematozorit value can be determined from the blood cell count signal and used to correct the immunoassay signal when whole blood is used.