Images such as 'therapeutic missile' are commonly used to present targeted drug delivery devices. The ballistic metaphor, reminiscent of Paul Ehrlich's 'magic bullet', has raised great expectations. Accordingly, chemists, physicists and engineers have worked hard to design smart 'missiles' delivering their load of drug to the target. While paying attention to the equipment of the nanodevice for the transport and molecular recognition for the delivery, they have to face the challenges posed by the messy environment of the body. We question the relevance of the missile metaphor, and suggest that an alternative ecological metaphor would be more appropriate. Such an approach, focused on interactions between the nanovehicle and the complex, versatile, heterogeneous biological milieu, seems more heuristic and promising. (C) 2013 Elsevier Ltd. All rights reserved.