The six minichromosome maintenance proteins (Mcm2–7) are required for both the initiation and elongation of chromosomal DNA, ensuring that DNA replication takes place once, and only once, during the S phase. Here we report on the cloning of a new human Mcm gene (hMcm8) and on characterisation of its protein product. The hMcm8 gene contains the central Mcm domain conserved in the Mcm2–7 gene family, and is expressed in a range of cell lines and human tissues. hMcm8 mRNA accumulates during G ₁ /S phase, while hMcm8 protein is detectable throughout the cell cycle. Immunoprecipitation‐based studies did not reveal any participation of hMcm8 in the Mcm3/5 and Mcm2/4/6/7 subcomplexes. hMcm8 localises to the nucleus, although it is devoid of a nuclear localisation signal, suggesting that it binds to a nuclear protein. In the nucleus, the hMcm8 structure‐bound fraction is detectable in S, but not in G ₂ /M, phase, as for hMcm3. However, unlike hMcm3, the hMcm8 structure‐bound fraction is not detectable in G ₁ phase. Overall, our data identify a new Mcm protein, which does not form part of the Mcm2–7 complex and which is only structure‐bound during S phase, thus suggesting its specific role in DNA replication.