Thirty-six specimens of Rhinobatos planiceps (Garman, 1880) "Pacific guitar fish" were acquired from the Chorrillos Fishmarket, Lima, Peru between September 2009 and August 2010 to assess the population dynamics of parasitic metazoa. Of the fish examined, 14 were females and 22 were males. The fish had an average total length of 85.0 ± 19.3 cm (27 to 125). Metazoan parasites were collected and counted using standard parasitological protocols. The parasite assemblage recorded a higher percentage of endoparasites than ectoparasites. All hosts showed infection with at least one parasitic species. Ten species were found with the following prevalence of infection and mean abundance: three species of Monogenea: Anoplocotyloides papillatus (41.6% and 1.1), A. chorrillensis (30.5% and 0.5) and Rhinobatonchocotyle pacifica (63.8% and 4.1), three species of cestodes: Rhinebothrium rhinobati (8.3%...