SUMMARYIndividuals belonging to five families, 12 genera, and 19 different species of bats from dengue endemic areas in the Gulf and Pacific coasts of Mexico were examined by ELISA, RT–PCR, and for the presence of dengue virus (DV) NS1 protein. Nine individuals from four species were seropositive by ELISA: three insectivorous,Myotis nigricans(four positives/12 examined),Pteronotus parnellii(3/19), andNatalus stramineus(1/4), and one frugivorousArtibeus jamaicensis(1/35) (12·86% seroprevalence in positive species). DV serotype 2 was detected by RT–PCR in four samples from three species (all from the Gulf coast – rainy season): two frugivorous,A. jamaicensis(2/9), andCarollia brevicauda(1/2), and one insectivorous,M. nigricans(1/11). The latter was simultaneously positive for NS1 protein. DV RT–PCR positive animals were all antibody seronegative.M. nigricansshowed positive individuals for all three tests. This is the first evidence suggesting the presence of DV in bats from Mexico.