The removal of arsenic (As) by means of nanofiltration (NF) membranes is discussed. In particular, the separation mechanism, state of the art and, limitations of NF related to arsenic removal are reported. Directions for new development are pointed out by analysis of the latest literature on the preparation of high performance NF membranes. The aim of this chapter is to give a comprehensive overview on the use of NF membrane-based processes for As removal, which not only provides a critical analysis of the current treatment status using membrane based processes, but also points out new development directions that may help the advancement of arsenic removal in a more energy efficient manner.