An immunoassay test slide for use in a dry chemistry analytical instrument includes a slide housing or case formed from two matable sections—a slide cover piece and a slide bottom piece. The slide housing defines an interior cavity in which is situated a sheet-like porous carrier matrix. The slide cover piece has an opening formed through the thickness thereof to expose a central portion of the fluid flow matrix so that a precise volume of fluid sample of blood, serum or the like, preferably pre-mixed with a conjugate reagent, and precise volumes of a wash reagent and a substrate (detector reagent), may be deposited on the matrix through the cover opening by a metering device of the analytical instrument. The bottom piece of the immunoassay test slide is transparent, and the slide is moved by a transport mechanism of the analytical instrument over a reflectometer or a fluorometer for performing reflectance or fluorescence measurements.