Ethics are, of course, a fundamental part of professional practice. There are different philosophical schools of thought relating to ethics and, although there are often degrees of overlap, they are characterized more by difference than harmony. Among these philosophical schools, one school that has received relatively little attention in the professional literature (and a waning level of interest in the philosophical literature) is that of existentialism. This article outlines some of the main points of ethical theory in the works of (...) Friedrich Nietzsche, one of the founders of existentialist thought, and Jean-Paul Sartre, the best known of the existentialist thinkers, as well as other contributors to existentialist thought. Possible developments in existentialist ethical theory since the time of Sartre are also sketched out, and these are linked to contemporary social work concerns. (shrink)