SUMMARY In August 1978 the Hluhluwe River, which runs through the Hluhluwe Game Reserve (Natal, South Africa), was polluted by toxaphene from a cattle dip tank. Faunal surveys were conducted to determine the impact of the insecticide on the fish and other vertebrate populations, and to monitor the recovery of the system. Fish survival was very low along 26 km of river immediately below the dip tank, and the distribution of mortalities strongly indicated previous lethal pollution. Most fish species had returned within one year, mainly from unpolluted tributaries, but populations were low. Fin-foots Podica senegalensis and crocodiles Crocody lus niloticue appeared to have declined. Below the die-off stretch, the bio-accumulation of toxaphene was demonstrated; and its implications to a number of rare and endangered species, particularly fish-eating birds, are discussed.