I consider four recently suggested difference between killing and letting die as they apply to active and passive euthanasia : taking vs. taking no action; intending vs. not intending the death of the person; the certainty of the result vs. leaving the situation open to other possible alternative events; and dying from unnatural vs. natural causes. The first three fail to constitute clear differences between killing and letting die, and "ex posteriori" cannot constitute morally significant differences. The last constitutes a (...) difference but is not morally significant. (shrink)