An order-picking system and method includes a pallet warehouse (12), preferably in terms of a high-bay warehouse, being used as a supply warehouse dedicated to a plurality of, preferably different, packing units (40) which are stored, preferably by one sort only, on pallets (14) in the pallet warehouse (12); a tray warehouse (24) which is used as a picking buffer for supplying connected order-picking stations with packing units (40), wherein trays (38) are stored in the tray warehouse which have been loaded with a pallet layer of packing units (40) before; a conveyor (22) which transports from the pallet warehouse to the tray warehouse trays (38) which are respectively loaded with a pallet layer of packing units, particularly across longer distances; and at least a rack-transport unit (36) for trays (38), the rack-transport unit allowing receipt of a plurality of trays being respectively loaded with a pallet layer.