An automated immunostaining apparatus having a reagent application zone and a reagent supply zone. The apparatus has a carousel slide support (24) supporting a plurality of slide supports (26) thereon, and drive means (48) engaging the carousel slide support (24) for consecutively positioning each of a plurality of slide supports (26) in the reagent application zone. The apparatus also has a carousel reagent support (10) having a plurality of reagent container supports (11) thereon, and drive means (14) engaging the carousel for rotating the carousel and positioning a preselected reagent container support (11) in the reagent supply zone. The apparatus also has a reagent delivery actuator means (18) positioned for engaging a reagent container (12) positioned on a container support (11) in the reagent delivery zone and initiating reagent delivery from the reagent container (12) to a slide supported on a slide support (26) in the reagent receiving zone.