The projected use of optical fibre is described to relay Ha light from the JET tokamak to a radiation-free environment. In the final two years of operation the device could produce through neutron emission an accumulated ionising dose of 1.5 x 108 rads(Si). The radiation-induced luminescence and optical absorption in the fibre are estimated. Whilst the former is negligible, the induced attenuation could reach 15 db. Photobleaching is an effective technique for reducing this loss. Continuous monitoring of the absorption, by transmitting a test signal through auxiliary fibres, would permit measurement of the absolute Ha intensity.