Abstract: Methods of and apparatus for washing an array of sites in high-density microplates or similar assay plates wherein the microplates or assay plates are washed in an inverted or nearly inverted position, rather than in an upright position. Preferably, the wash liquid is dispensed upwardly in the form of a sheet from a nozzle mounted on a spray bar as the spray bar moves relative to the microplate or assay plate. After washing, the microplate or assay plate is dried with a stream of gas such as air, also preferably blown upwardly in the form of a sheet.