In recent years, droplet microfluidics has become an important tool for the development of precision medicine. Droplets are uniformly and efficiently produced in microfluidic devices on the scale of picoliters to nanoliters. The droplets act as individual microreactors and facilitate high throughput and quantitative analysis, thus providing an attractive platform for the analysis of biomolecules or single cells in precision medicine. In this chapter, we will review the principles and techniques of droplet microfluidics, and the important applications of droplet microfluidics for precision medicine.