A novel technique for depositing non-centrosymmetric Langmuir-Blodgett films onto side-polished, single-mode optical fibres has been developed. The main feature is the ability to transfer the monolayer only on the up-stroke and thus, for suitable film-forming materials, to fabricate non-centrosymmetric Z-type structures in which the molecular dipoles are aligned. Strong second-harmonic generation has been observed from a multilayer film of E-N-octadecyl-4-[2-(4-dibutylaminophenyl)ethenyl]quinolinium octadecylsulphate deposited onto a single-mode optical fibre.