Abstract: A microtiter plate reader is disclosed which allows visual examination of the contents of the wells of a microtiter plate having an array of wells. The microtiter plate reader includes supporting means for supporting the microtiter plate with the wells opening generally upwardly and a light emitting surface is adapted to extend under a microtiter plate so held. Regions of reduced light emission on the light emitting surface are arranged in an array corresponding in relative position to a selected portion of the array of microtiter plate wells. Locator means are provided for locating the microtiter plate with respect to the array of regions of reduced light emission to allow selective alignment of the wells with the dark regions, providing a dark background to the bottom of the wells which are then illuminated indirectly. The wells can be illuminated directly when the dark regions are out of alignment with the wells.