The results of a de Haas-van Alphen investigation of Nb3Sb, a compound having the β-W or A-15 structure, are presented. Two families of strong frequencies are consistent with a location of surfaces at the point M in the simple cubic Brillouin zone. The larger of the two could be an open surface, but the data are inconclusive because of the occurrence of several weak frequency branches. The data are somewhat consistent with the band calculations of Mattheiss for Nb3Sn if the Fermi level is shifted. © 1977 The American Physical Society.