the first dengue fever epidemic in the state of rond？nia (western region of brazil) was recorded in 1997, without laboratory confirmation. following this, there was an epidemic in manaus, in the neighboring state of amazon, in 1998, in which denv-1 and denv-2 viruses were isolated from patients. in the present paper, the serotype characterization of the dengue virus isolated from patients with clinically suspected dengue in porto velho, rond？nia, between 2001 and 2003 is described. one hundred and fifty blood samples were collected between the first and fifth days of symptoms. seventy samples of virus isolates were subjected to dengue identification by means of rt-pcr using universal primers for the ns1 gene of denv, which amplifies a 419 bp fragment. the amplicons obtained were subjected to enzymatic digestion to characterize the viral serotypes. all the samples analyzed were denv-1. a nucleotide sequence randomly selected from one amplicon, which was also denv-1, presented 98% similarity to sequences from southeast asia that were obtained from genbank.