Source: Player's Handbook
You know how to fight in melee without being able to see your foes.
Benefit: In melee, every time you miss because of concealment, you can reroll your miss chance percentile roll one time to see if you actually hit (see Concealment). An invisible attacker gets no bonus to hit you in melee. That is, you don't lose your positive Dexterity bonus to Armor Class, and the attacker doesn't get the usual +2 bonus (see Attack Roll Modifiers). The invisible attacker's bonuses do still apply for ranged attacks, however. You suffer only half the usual penalty to speed for being unable to see. Darkness and poor visibility in general reduces your speed to three-quarters of normal, instead of one-half.
Special: The Blind-Fight feat is of no use against a character who is the subject of a blink spell).