Ultra-fine DNA bridges (UFBs) are a recently identified class of mitotic DNA structures that cannot be visualized using conventional DNA staining methods (e.g. using DAPI). Their existence can currently only be revealed by immuno-fluorescent staining for proteins that bind to them, including PICH and BLM. UFBs become visible in the anaphase of mitosis, and can persist into telophase in rare cases. There are at least three different types of UFBs that can be distinguished according to the chromosomal loci from which they originate. However, it remains largely unknown how these UFBs are generated or resolved in the cell. In this article, we will review our current understanding of different types of UFBs and the potential functional role of the proteins that have been shown to be associated with them.