Polyamines stabilise nucleic acids against chemical and enzymatic degradation, facilitate the formation of secondary and tertiary structures and enhance cellular uptake. Therefore methods for the syntheses of polyamine–nucleic acid conjugates are of interest. A route for the syntheses of RNA–spermine conjugates has been developed. The polyamine was introduced to the C-5 position of uridine via an ethyl tether and the molecule elaborated into a synthon suitable for oligoribonucleotide assembly. The resultant oligomers were components of the hairpin ribozyme. Characterisation of the spermine-conjugated catalytic RNA revealed that attachment of the polyamine was well tolerated in three of four positions, namely U41, U37 and U34, suggesting that conjugation to C-5 brings about minimal structural perturbation.