Electronic retina is a combination between in situ signal processing and image sensing on a same silicon chip. This smart image sensing, realizable in commoncmos technology, is a valuable technique in real-time vision systems. In order optimize the global performance of a vision machine where different levels of processing are needed, this technique can not be considered simply as an intelligent image sensor design problem. Because the local onsensor information processing in an electronic retina should be placed in a more general context including algorithms, architectures and applications. This paper tries to give an overview on the electronic retina based vision systems and especially on the roles that an electronic retina can play in real-time vision systems.