In a rodent (Rattus norvegicus) survey in Buenos Aires province, metacestodes of tapeworms were found encysted in the liver of the host. The aim of this work was the morphological and molecular identification of this parasite. To achieve the molecular characterization of the parasite, ribosomal (28S) and mitochondrial (COI) DNA were amplified and sequenced. Based on both morphological and molecular data using bioinformatic tools, the metacestode was identified as Cysticercus fasciolaris. The adult form of this tapeworm (Taenia taeniaeformis) commonly infects felid and canid mammalian hosts. This is the first report on the molecular identification of Cysticercus fasciolaris in Buenos Aires province (Argentina).