North-south pointing tendency is very strongly developed in mounds of a 'magnetic' termite, Amitermes laurensis, in northern Australia. Determination of orientation in 248 termitaria in Arnhem Land showed a total range from 349 deg to 030 deg (true). Angular means from each of four separate study sites were 007 deg 39' (n = 47), 010 deg 35' (n = 101), 006 deg 56' (n = 50) and 008 deg 34' (n = 50). Orientation of mounds built among trees of savannah woodland is not less accurate than that of mounds built on open plains. The shape of mounds in plan view is variable. They may be symmetrical, or show concavity of either eastern or western face. Shape-frequency distributions for each locality were heterogeneous, even between localities in close proximity. It is suggested that mound shape may be determined genetically rather than by environmental factors.