Abstract De Haas-van Alphen oscillations in the low-temperature, magnetic susceptibility have been investigated in fields up to 100 kG for the hexagonal, intermetallic compound AuSn at the equi-atomic composition. Results are presented for the frequency measurements in the {0001}, {10 1 0} and {11 2 0} planes, together with cyclotron effective masses and Dingle ‘scattering temperatures’. The 1-OPW model, extending into eight zones, the first two of which are filled, has been constructed according to both the single and double zone schemes, and the extremal cross-sectional areas have been computed. Spin-orbit effects are found to be important in AuSn and the experimental results are interpreted in terms of a model for the Fermi surface based on the single zone scheme, but with limited magnetic breakdown. Between zones 3 and 4, breakdown is complete at magnetic fields > 30 kG, but no major breakdown phenomena were observed below 100 kG between zones 5 and 6. An estimate of 0·16 eV is obtained for the spin-orbit gap relevant to the latter case, corresponding to a breakdown field of ≈ 250 kG. The derived model for the Fermi surface indicates that in the absence of breakdown between zones 5 and 6, AuSn is a compensated metal supporting open orbits along 〈001〉, 〈 10 1 0〉 and 〈 11 2 0〉. These conclusions are in agreement with the high-field, galvanomagnetic properties of AuSn.