The solid-state packing arrays of ten 4-chloro substituted 2-aminopyrimidines have been examined and the occurrence of N-H-Cl hydrogen-bonding associations in those structures discussed. The ten compounds were 4,6-dichloropyrimidine 1, 2-amino-4-chloro-6-(4carbamoylpiperidinyl)pyrimidine hemihydrate 2, 2-amino-4-chloro-6-(4fluorophenylthio)pyrimidine 3, 2-amino-4-chloro-6-(1-phenylethylamino)pyrimidine 4, 2amino-4-chloro-6-benzylaminopyrimidine 1 6 hydrate 5, 2-amino-4-chloro-6-isopropylaminopyrimidine 6, 2-amino-4-chloro-6-(4-(2,3-dimethylphenyl)piperizino)pyrimidine hydrate 7, 2amino-4,6-dichloro-5-phenylpyrimidine 8, 2-amino-4-chloro-6-dimethylamino-5-phenylpyrimidine 9 and 2-amino-4-chloro-5-phenyl-6-thiomorpholinopyrimidine 10. The single-crystal xray structures of 1-4 have been previously reported while the structures of 5-10 are presented in this paper. All packing motifs, except compound 2, exhibit characteristic R 2 2 (8) hydrogenbonded 2-aminopyrimidine dimers, to varying degrees of polymerisation. Only compounds 8 and 9 include N-H-Cl interactions, which for compound 8 is a three-center association in addition to a N-H-N interaction.