Parts of the Masai Mara area are characterised by oval, flat, bare arenas. These were found to be underlain by nests of the fungus-growing termite Odontotermes fulleri (Isoptera, Termitidae, Macrotermitinae). The structure of the nests and the fungus combs are described and illustrated. Dry weights of the different castes of the termites from a series of nests are reported. Possible functions of the arena are briefly discussed.