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) A and Zn-I distances ranging from 2.5471 (13) to 2.5673 (13) A. The molecular structure features a zigzag polymeric chain. Face-to-face pi-pi stacking interactions between adjacent bipy ligands stabilize the structure.