Trichostrongylus angistris n. sp. was found in the abomasa of 13 red duiker Cephalophus natalensis A. Smith, 1834, culled in the Charter's Creek Nature Reserve, Natal. The species is closely related to Trichostrongylus minor Mönnig, 1932 and can be differentiated from it by the shorter dorsal ray and the different shape of the gubernaculum and spicules. The shoes of the spicules of T. minor are set at an angle to the long axis, while those of T. angistris are curved. Upon re-examination, the Trichostrongylus spp., tentatively identified as Trichostrongylus capricola Ransom, 1907 and Trichostrongylus vitrinus Looss, 1905, proved to be T. angistris. In this paper, T. angistris is compared with T. capricola and T. vitrinus and T. minor is redescribed.