Histone H3 is specifically phosphorylated during both mitosis and meiosis in patterns that are specifically coordinated in both space and time. Histone H3 phosphorylation may initiate at different phases of the cell division in different organisms, but metaphase chromosomes are always found to be heavily phosphorylated. Upon exit of mitosis/meiosis a global dephosphorylation of H3 takes place. Potential candidates for H3 kinases are described and their hypothetical mechanism of action on highly condensed chromatin templates is discussed. In addition, a novel hypothesis for the role of histone H3 phosphorylation during cell division is proposed. This hypothesis, termed the 'ready production label' model, explains the results in the literature and suggests that phosphorylation of histone H3 is a part of a complex signaling mechanism.