This article considers the ethical aspects of the question: should a scientist engage in war-related research, particularly use-inspired or applied research directed at the development of the means for the better waging of war? Because scientists are simultaneously professionals, citizens of a particular country, and human beings, they are subject to conflicting moral and practical demands. There are three major philosophical views concerning the morality of war that are relevant to this discussion: realism, just war theory and pacifism. In addition, (...) the requirements of professional codes of ethics and common morality contribute to an ethical analysis of the involvement of scientists and engineers in war-related research and technology. Because modern total warfare, which is facilitated by the work of scientists and engineers, results in the inevitable killing of innocents, it follows that most, if not all, war-related research should be considered at least as morally suspect and probably as morally prohibited. (shrink)