Abstract: A miniature reaction container for conducting reactions with precise micro-liter volumes of liquid reactants, reagents and samples for the purposes of enzyme assay procedures, comprises a tubular reaction chamber made from a transparent wettable plastics material and an inlet tube made from a transparent non-wettable material, such as Teflon. Both the chamber and the inlet tube may be capillary tubes and the volume of the chamber should not exceed 30 .mu.l. For the purposes of a particular assay procedure, the chamber may be pretreated so as to have a reactant adhered or chemically bonded to its inside surface. With a plurality of such reaction containers, a multiplicity of reaction mixtures may be prepared and incubated simultaneously. To this end, the containers, which may or may not have been pretreated with reactant, are mounted in a slidable assembly together with syringes.