The circumstances of the deaths of 17 badgers in south-eastern England are described together with post-mortem examinations. The livers of eight animals were analysed to detect the levels of organochlorine insecticides. All contained dieldrin (0.01 to 46.3 ppm), five contained DDT and/or its derivatives (0.30 to 19.2 ppm) and three contained heptachlor epoxide (1.9 to 4.4 ppm). It is concluded that five of the 17 died after road accidents whilst of the remainder, six certainly and six very probably died of dieldrin poisoning. The behaviour of one poisoned badger maintained in the laboratory is described. The amounts of dieldrin contained and consumed by the badgers are discussed together with the possible sources of the poison.