Background: Lyme disease is a tick-borne human disease caused by the spirochete Borrelia burgdorferi. Main vectors of Lyme disease are ticks of the Ixodes and Amblyomma genera. Cases with clinical manifestations of Lyme disease and favorable responses to antimicrobial agents have been reported in Chile, some of them with erythema migrans, the hallmark of B burgdorferi infection. Aim: To detect the presence of B burgdorferi in Chilean ticks. Material and methods: A total of 62 ticks were recollected from wild rodents and cervidae in the Southern region of Chile. Infected and non infected ticks of the species Ixodes ricimus, were used as controls. Insects were homogenised and B burgdorferi was detected using classical and nested polymerase chain reactions. Results: B burgdorferi was not detected in the studied ticks. Conclusions: Although all the elements required for the enzootic cycle of B burgdorferi are present in Chile, its direct detection in Chilean ticks using the nested polymerase chain reaction assay was negative. (Rev Méd Chile 2001; 129: 270-6).