X-ray analysis of the title compound reveals three crystallographically distinct cations of 1,9-diethyladeninium, two iodide anions and one triiodide anion in the asymmetric unit, giving six residues and the formula 3C9H14N5+.I3-.2I-. Standard purine nomenclature is used to identify the atoms of each adenine moiety. Hydrogen bonding is observed between atoms N6 and N7 of a pair of cations [N...N=2.885 (4)/2.902 (3) and 2.854 (3)/2.854 (3) A], with additional hydrogen bonding to I- anions via the other N6 H atom [N...I=3.708 (3), 3.738 (3) and 3.638 (3) A]. The triiodide anion is not involved in hydrogen bonding. The bond lengths and angles of the 1,9-diethyladeninium cations are compared with literature values and confirm the formation of the imine tautomer.