Theoretical study of the hyperpolarisabilities beta and gamma of aniline oligomers is presented. The results obtained for beta at the AM1/TDHF level are promising for the emeraldine form, indicating a potential use as a second-order nonlinear optical material. The calculations of static cubic hyperpolarisability of trimers agree with the experimentally observed trends for polyaniline. (C) 2002 Published by Elsevier Science B.V.