A modular lighting system, comprising at least one module and auxiliary components which can be assembled together; the module comprising a support core, extending along an axis; a plurality of LEDs, arranged on at least one face of the core and axially spaced along the axis; a light body positioned in front of the LEDs and at least partly around the LEDs and having a lighting surface which transmits the light emitted by the LEDs to the surrounding environment; the modules and the auxiliary components are joined to each other by respective concealed mechanical and electrical connection devices, which are completely housed and concealed inside the modules and/or the auxiliary components.