It is our pleasure to introduce this IEEE Design & Test Special Issue on Microfluidics: Design and Test Solutions for Enabling Biochemistry on a Chip. Recent advances in microfluidics-based biochips, also known as lab on a chip or bio-MEMS, have led to the design of a plethora of new devices for the automation of a wide class of laboratory procedures in biochemistry and molecular biology. These devices elegantly integrate fluidics, microelectronics, biochemistry, and sensing on a single flow-based or droplet-based platform. They enable the precise control of nanoliter-scale biochemical samples and reagents and automate highly repetitive laboratory tasks by replacing cumbersome equipment with miniaturized systems. As these chips provide ultrasensitive detection at a significantly lower cost per assay than traditional methods, they find diverse applications in clinical and diagnostic pathology, point-of-care healthcare services, and in drug design, among others. As the use of microfluidics-based biochips continues to increase, their complexity is expected to become significantly large due to the need for executing multiple and concurrent assays on the chip, as well as for ensuring more sophisticated control mechanisms to handle resource management. Time to market, testability, fault tolerance, and cyber-physical issues are also expected to emerge as new design considerations. As a result, current fullcustom design techniques will not scale well for larger designs. There is a need to deliver the same level of computer-aided design (CAD) support to the biochip designer that the semiconductor industry now takes for granted. This special issue highlights recent investigations regarding various design and test solutions for microfluidic biochips. The selected articles include two tutorial articles and five regular articles. The articles are briefly summarized.