Abstract: Miniaturized, self-contained apparatus for conducting bio-chemical reactions and analyses is formed in a compact structure made from a substrate which includes a plurality of reaction chambers and a plurality of analysis chambers which are in fluid communication with the reaction chambers. Independently controllable heaters and coolers are positioned in thermal contact with the reaction chambers to permit parallel processing of biological samples at different temperature cycles. The apparatus is especially useful for performing and analyzing the results of a polymerase chain reaction.