The eukaryotic GINS complex is essential for the establishment of DNA replication forks and replisome progression. We report the crystal structure of the human GINS complex. The heterotetrameric complex adopts a pseudo symmetrical layered structure comprising two heterodimers, creating four subunit-subunit interfaces. The subunit structures of the heterodimers consist of two alternating domains. The C-terminal domains of the Sld5 and Psf1 subunits are connected by linker regions to the core complex, and the C-terminal domain of Sld5 is important for core complex assembly. In contrast, the C-terminal domain of Psf1 does not contribute to the stability of the complex but is crucial for chromatin binding and replication activity. These data suggest that the core complex ensures a stable platform for the C-terminal domain of Psf1 to act as a key interaction interface for other proteins in the replication-initiation process.