The effect of reverberation on speech is to cause it to sound distant and spectrally distorted and can also reduce intelligibility. Dereverberation is therefore an important speech enhancement process for hands-free terminals. This is a blind problem and currently an unsolved problem. This paper reviews existing ap- proaches and discuss current work on this topic in two categories - one based on processing of the LPC prediction residual and one based on a combination of blind channel estimation and channel inversion. The measurement of (de)reverberation is discussed.