What interests Deleuze most, in his texts on psychoanalysis, is the death instinct. He devotes a chapter of Présentation de Sacher-Masoch to this subject, as well as long pages of Répétition et Différence and innumerable passages in L'Anti-Oedipe. Though the controversy with psychoanalysis may touch on many points, it is clear that, deep down, it is located there, on the element Guattari and Deleuze reckon to be the most interesting, the most revolutionary and the most essential. What were they looking for in the death instinct? Why should the whole debate with psychoanalysis turn on this obscure concept? This essay offers some ideas for analyzing these questions.