The crystal structure of the self-complementary DNA octamer d(GGCATGCC) has been determined to a resolution of 2.38 Å and R factor of 17.1%. The structure is an A-DNA octamer duplex with Watson–Crick base pairing along its length. This sequence extends the investigation of octamer duplexes of the type d(GGX4CC) which assume P61 packing within the crystallographic unit cell. The A-DNA duplex is non-linear with a helix axis curvature of 7° and bending towards the DNA minor groove. In view of the biological importance of protein recognition of some A-DNA sequences the minor-groove geometry and helix-axis curvature for this structure is compared with all others of the type d(GGXATXCC).