The present invention is directed to an automatic chemical analytical apparatus for analyzing liquid samples. In order to provide a fully automatic transport of sample tubes containing samples to be analyzed, the apparatus includes a sample processing unit, a sample transport arrangement for transporting the sample racks from a rack supply unit to a rotatable sample rack carrier in the sample processing unit and vice versa, and a computer for controlling and coordinating the operation of the sample transport arrangement and an automatic pipetting unit. The sample processing unit includes the automatic pipetting unit and the rotatable sample rack carrier that accommodates a plurality of sample racks. Each sample rack, in turn, accommodates a plurality of sample tubes.