The title compound, [ ZnI2( bipy)] n ( bipy is 4,4'-bipyridine, C10H8N2), has been prepared by the hydrothermal reaction of ZnI2 and bipy at 433 K. Each Zn atom is coordinated by two N atoms from two different bipy ligands and by two I atoms in a distorted tetrahedral geometry, with Zn - N distances ranging from 2.068 ( 7) to 2.101 ( 8) angstrom and Zn - I distances ranging from 2.5471 ( 13) to 2.5673 ( 13) angstrom. The molecular structure features a zigzag polymeric chain. Face- to- face pi-pi stacking interactions between adjacent bipy ligands stabilize the structure.