NASA Glenn Research Center 1 article published in JoVE Biology Reduced-gravity Environment Hardware Demonstrations of a Prototype Miniaturized Flow Cytometer and Companion Microfluidic Mixing Technology William S. Phipps*1, Zhizhong Yin*1, Candice Bae1, Julia Z. Sharpe1, Andrew M. Bishara2, Emily S. Nelson3, Aaron S. Weaver3, Daniel Brown4, Terri L. McKay3, DeVon Griffin3, Eugene Y. Chan1 1DNA Medicine Institute, 2Harvard Medical School, 3NASA Glenn Research Center, 4ZIN Technologies Spaceflight blood diagnostics need innovation. Few demonstrations have been published illustrating in-flight, reduced-gravity health diagnostic technology. Here we present a method for construction and operation of a parabolic flight test rig for a prototype point-of-care flow-cytometry design, with components and preparation strategies adaptable to other setups.