Spermine, an aliphatic polycationic molecule found in all cells, plays an essential role in cell growth and differentiation. At present, there is no thorough understanding of how polyamines exert their physiological effects. Spermine is known to interact both with DNA and with proteins, yet the details of these interactions and the molecular basis of the biological function of spermine are poorly understood. There is evidence in the literature that spermine interacts with different forms of DNA in distinct and divergent modes. We have confirmed this and have characterised the complexes of spermine with duplex B-DNA and G-quadruplex DNA using a specifically 13C-labelled spermine and advanced NMR techniques to take advantage of the specific isotope label on spermine. Quantitative analysis of the field dependence of 13C T1 and T2 relaxation times and homonuclear and heteronuclear NOEs have been used to characterise the dynamics of spermine in the presence of different forms of DNA. The fast internal motion of spermine is slowed by two orders of magnitude on binding to all forms of DNA but is still independent of the tumbling of DNA. Only in the case of folded DNA quadruplexes is there evidence of a slower motion associated with overall tumbling of the macromolecular structure and an exchange process between two or more different binding sites. A detailed description of this work has recently been published in the European Biophysics Journal.