It is demonstrated that metamaterial transmission lines based on complementary split rings resonators (CSRRs) can be applied to the design of quadrature phase shifters with compact dimensions and broad operational bandwidth. The structure consists of a Y-junction with output lines exhibiting a phase difference of 90°, these lines being artificial and implemented by means of CSRRs. The device is compared to a conventional implementation. From the characterisation of both devices it is concluded that the phase difference is preserved over a wider band in the metamaterial-based phase shifter. © The Institution of Engineering and Technology 2007.