Who are you angry at? Why are you angry? What is the outcome of your anger in your dream? Being angry in a dream often represents an emotion we want to have in waking and will not allow ourselves to experience. This reflects the fact that anger can be destructive and sometimes ends up being treated as a taboo in our personality. The fact that it comes out in dreams may be attributed to the id.
People who dream of being angry often have difficulty expressing the emotion constructively in waking life. Anger is a reaction to a perceived threat. As such, anger reflects our feeling that we are being denied what is ours by necessity or by right.
Dreams that contain anger may often serve as an insightful beacon into our waking relationships. Sometimes, you may find yourself dreaming of being angry at someone who never angers you in waking life. This may simply be an indication that they are not perfect; a sort of check that reminds you that they are human.