Abstract: An apparatus for processing and analyzing blood serum includes an input rack for holding test tubes containing whole blood specimens and separator gel, a centrifuge, an optical sensing unit for receiving centrifuged test tubes and generating output signals indicative of whether the centrifuging was successful and, if it was, the boundary position between the separator gel and the blood serum, and a computer connected to receive and analyze the output signals of the optical sensing unit. An aspirator/dispenser needle unit is positioned above the sensing unit and is capable of lowering a needle, under the control of the computer, to puncture the stopper of a test tube and then withdraw blood serum.