Coarse-grained molecular dynamics simulations have been used to explore the interactions of C-60 and its derivatives with lipid bilayers. Pristine C-60 partitions into the bilayer core, whilst C-60(OH)(20) experiences a central energetic barrier to permeation across the bilayer. For intermediate levels of derivatization, e. g. C-60(OH)(10), this central barrier is smaller and there is an energetic well at the bilayer/water interface, thus promoting entry into cells via bilayer permeation whilst maintaining solubility in water.