contribute for the loss of the physical-mechanical properties of the reinforced concrete (RC) structures. When the bond between the concrete and the reinforcing rebars are affected, the results can be extremely dramatic and unpredicted. In this work, an optical fiber device for the monitoring of the bond-ship of old RC structures, where less intrusive techniques need to be taken into account, is proposed and tested. The sensor developed is based on the fiber Bragg grating (FBG) technology, inscribed in silica optical fiber. An experimental campaign was carried out in a RC sample, following the recommendations of the Annex D of the EN 10080. The results showed that the bond-slip optical sensors are capable of measuring micro-displacements, with lower intrusiveness. Therefore, they can be used for monitoring the bond-slip of old RC structures as way of to collect information, essential to assist the owners to adopt cost effective, efficient and safer maintenance measures.