Provided are a complementary metal oxide semiconductor (CMOS) image sensor including two types of device isolation regions and a method of fabricating the same. The CMOS image sensor includes a first active region of a semiconductor substrate in which a photodiode is formed; a second active region of the semiconductor substrate connected to a first side of the first active region; a first device isolation region of the semiconductor substrate comprising an insulating layer that surrounds the second active region and bounds the first side of the first active region and a second side of the first active region disposed opposite to the first side of the first active region; and a second device isolation region of the semiconductor substrate bounding at least two opposite sides of the first active region without contacting the second active region, wherein the second device isolation region is doped with impurities