Abstract: A laboratory organizer unit includes an enclosed housing with a storage area containing a plurality of racks for storing specimen containers, the racks movable throughout the storage area to permit access to all of the racks from an opening in the upper end of the storage area. A robotic transfer apparatus is operable to insert and retrieve specimen containers from selected racks in the storage area and move them between the storage area and a buffer area on the housing, as well as between the buffer area and a conveyor located adjacent the housing. The conveyor is of a type which transports specimen carriers having a specimen container therein, and the buffer area includes a rack for intermediate storage of specimen containers. The buffer area thereby permits the transfer apparatus to retrieve and load specimen containers on specimen carriers on the conveyor, while awaiting an appropriate rack to move into position in the storage area.