Chromosomes are condensed form in all living organisms. In prokaryotes, three groups of chromosome condensin complexes have been identified, Smc/ScpAB, MukBEF and a related MksBEF. To date, the architecture of Smc/ScpAB, which is much more prevalent over the other two groups, has been partially known. Herein, I provide the architectural view of Smc/ScpAB by elucidating the structures of two subcomplexes, an archaeal SMC’s ATPase domain bound to the ScpA’s C-terminal winged-helix domain (C-WHD) and a C-WHD-truncated bacterial ScpA bound to ScpB. The intersubunit interactions in Smc/ScpAB are surprisingly different from those in MukBEF. In particular, both the N- and C-termini of ScpA interact with SMC, resulting in the ring-like holocomplex structures with asymmetrically linked SMCs by the ScpAB complex. The architecture of Smc/ScpAB is very different from that of MukBEF and therefore the action mechanism is unlikely to be similar in the two condensins. Preliminary data point that the hinge domain of SMC could be opened in the ATPase cycle.