A reagent container system for a reagent analyzer, in particular an automatic reagent analyzer, is disclosed. The system includes a first reagent container cassette provided with a first set of openings each being capable of containing a reagent therein, and a second reagent container cassette provided with a second set of openings each being capable of containing a reagent therein. The system provides the first and second reagent container cassettes at least in a storage configuration in which the container cassettes are joined together such that a longitudinal side of the first reagent container cassette is facing a longitudinal side of the second reagent container cassette. Wherein, by relative displacement, the first and second reagent container cassettes are displaceable between the storage configuration and a use configuration in which a transverse side of the first reagent container cassette is facing a transverse side of the second reagent container cassette.