Calcium ions are one of the key mediators in the cell. Their action takes place, inter alia, through the calcium-binding proteins. Among the calcium-binding proteins are a growing number of discovered in the past ten years, protein motif "EF-hand" which form the so-called family. Sensors neuronal calcium (NCS, Neuronal Calcium Sensors). It belong to, inter alia: rekoweryny, frekweniny protein GCAP, VILIP protein. Their common feature is the presence of a characteristic structure and in certain nerve cells, which suggests that there remain a precise function. The majority of the NCS proteins, however, has not been elucidated and is the subject of many research teams in the world. In this paper we review the current state of knowledge on this interesting and important group of proteins.