The present paper seeks to closely explore Kurt Vonnegut‟s Slaughterhouse-Five in terms of Judith Herman‟s surveys and categorization of post-traumatic stress disorder symptoms. It is an attempt to analyze the conflict between the will to deny horrible events experienced by the protagonists of the novel in World War II and the will to proclaim them aloud. The psychological distress symptoms including the inability to sleep, lack of concentration, flashbacks and state of surrender are thus investigated in the narrator and Billy Pilgrim as the two figures who are suffering from PTSD. These symptoms are analyzed in a way to call attention to the existence of unspeakable secret and simultaneously as means to deflect attention from it. The protagonists are both subjected to the dialectic of trauma in that they find it difficult to remain clearheaded, to see more than a few fragments of the picture at one time, and to retain all the pieces and to fit them together. It is even more difficult to find a language that conveys persuasively what they have seen.