The presented paper reviews the latest literature data on SMCs proteins (Structural Mainte- nance of Chromosomes) which contribute to regular chromatid segregation in mitosis and meiosis. SMC proteins are high molecular weight proteins with ATPase activity. These proteins are highly conserved in eukaryotes and prokaryotes. The structure of SMCs proteins is very specific, each SMC subunit contais two globular domains and a helical domain, called arm. Conservative motifs Walker A and Walker B are located at the N-terminal and C-terminal ends of the head domain.