This study describes the parasitic fauna and the host-parasite relationship of Semaprochilodus insignis Jardine, 1841 from Coari Lake, a tributary of the middle Solimões River (state of Amazonas, Brazil) in Central Amazonia. Of 56 fish examined, 23.2% had gills parasitized by Gyrodactylus Gemini Ferraz, Shinn & Sommerville 1994 (Monogenoidea: Gyrodactylidae), and the intestine by Procamallanus inopinatus Travassos, Artigas & Pereira, 1928 (Nematoda: Camallanidae). The highest rates of infection were caused by G. gemini. Even though the relative condition factor (Kn) was not affected by parasitism, there was a positive correlation between the intensity of both helminthes, the Kn and the total length of the hosts. This is the first report on the parasitic fauna of S. insignis with occurrences of G. gemini and P. inopinatus for this Neotropical host fromthe Amazonia.