H1 histone family, member 0 (H1F0) is a member of the H1 histone family of nuclear proteins which are a component of chromatin in eukaryotic cells. It's involved in maintaining the structure of chromatin by packing the "beads on a string" sub-structure into a high order structure. The lysine-rich H1 histone family in mammals includes eleven members. In higher eukaryotes all H1 variants have the same general structure, consisting of a central conserved globular domain and less conserved N-terminal and C-terminal tails. These tails are moderately conserved among species, but differ among variants, suggesting a specific function for each H1 variant. Studies on the role of particular subtypes at specific developmental stages in lower eukaryotes, but also in vertebrates suggest that specific subtypes of H1 participate in particular systems of gene regulation.