Mn-Sb-Bi thin films were prepared by successive r.f. or d.c. sputter deposition of elements in a trilayer configuration with either Bi or Sb as the first layer. In-situ transmission electron microscopy (TEM) observations were conducted to investigate the morphology and structure of the films, both as-deposited and after annealing at 623 K for 5 h in a high vacuum furnace. The morphology and structure of all the films are highly dependent on the first-deposited layer. For the annealed film in the configuration of Mn/Bi/Sb// a well-defined hexagonal Mn-Sb-Bi NiAs type structure with the c-axis perpendicular to the film surface was observed. The grain size (100 nm) was two times larger than that of the film having Bi as the first layer. In both kinds of film the easy direction of magnetisation was very close to the film plane. The polar Kerr rotation from the two film structures was approximately 1.0degrees.