An apparatus and method for measuring or comparing rheological properties of fluid samples in parallel is disclosed. The apparatus includes a plurality of sensing elements which are comprised of flow channels and reservoirs in fluid communication. The channels provide flow paths for the fluid samples which are initially contained within external reservoirs. The method includes flowing the fluid samples at variable rates and monitoring simultaneously sample flow rates from the reservoirs through a plurality elements for one or more increments of time. The disclosed method is capable of measuring or comparing rheological properties of at least two fluid samples simultaneously. Useful flow rates monitoring devices include optical array sensors and image analysis systems.