This thesis entails the synthesis and in vitro evaluation of a number of cationic lipids. These lipids include those with a dimethylamine (DMA) headgroup or trimethylamine (TMA) headgroup, a seven or eleven carbon chain length or a mixed carbon chain length within the hydrophobic domain. The lipids are characterised by acyclic or macrocyclic hydrophobic regions that are either saturated or unsaturated. The work describes the successful synthetic routes to these various different cationic lipids and looks at the biological effects that are had on toxicity, transfection and DNA binding, when the various different structural aspects of the cationic lipids are changed.