The use of scintillating fibres as positron detectors in μSR experiments is discussed. Experimental tests and numerical simulations show that 1 mm thick fibres represent an optimum choice between a sufficiently high signal level and a good spatial resolution. A comparison of decay positron detection efficiency with that of electrons from common ⁹⁰Sr sources shows that the existing results with beta emitters could be transferred almost unvaried to fibres for use in μSR spectrometers. Thanks to a quantum efficiency above 50% and to a continuously improving gain (currently at 1 × 10⁶), the newly developed Geiger-mode avalanche photodiodes (G-APDs) represent the most promising choice as associated photon detectors.