Background Microglia are the resident immune cells in the brain that are sensitive to changes in their local environment. They respond to pathogen or danger signals by triggering brain immune response. Many drugs working on the nervous system can target microglia as well as neurons. Caffeine is the most widely consumed psychoactive drug across various age groups worldwide. However, little is known whether caffeine can affect microglia function. This study is aimed to examine whether caffeine regulates microglia functions and autophagy is involved in the action of caffeine on microglia, since autophagy plays a critical role in cellular immune response. ⓒ 2016 DGIST