The sensing of nucleic acids by pattern recognition receptors is a central feature of innate immunity and is mediated by two types of receptors, Toll-like receptors and cytosolic receptors. Indeed, DNA, be it pathogen-derived or self-derived, can potently trigger the innate immune system; and much attention has been focused on the regulation of the DNA-sensing system(s) in the context of protective and pathological immune responses. An accumulating body of evidence has demonstrated that in addition to the membrane-bound type DNA-sensing receptor TLR9, there are cytosolic DNA receptors that can also evoke these responses. In particular, DAI (DLM-1/ZBP1), Trex1, and other regulators of the cytosolic DNA-sensing system have recently been identified and characterized. Here, we summarize our current understanding of how cytosolic DNA receptors contribute to the regulation of innate immune responses and discuss the complexity of the cytosolic DNA-sensing system as well as its future prospects.