More than 50 million people are currently estimated to be infected with intestinal trematodes, including at least 18 million people infected by fishborne trematodes (FBT) around the world. Heterophyid (Heterophyidae) and echinostomatid flukes (Echinostomatidae) are regarded as the most important groups found in the intestinal tract of humans [1,2]. With regard to heterophyids, 10 species in 7 genera, i.e. [1,2]. Among these fish hosts, yellowfin goby, Acanthogobius flavimanus, are sometimes heavily infected with the metacercariae of heterophyid flukes, and are popularly eaten raw by many residents in coastal areas of . However, echinostomatid metacercariae have never been reported from yellowfin gobies in the Republic of Korea.Therefore, we performed an epidemiological survey to know the infection status of FBT metacercariae in yellowfin gobies collected in Shinan-gun and Muan-gun, Jeollanam-do (province), the Republic of Korea.On September 2006, 14-15 gobies were collected, and examined by artificial digestion method (Table 1). Trematode metacercariae were segregated, collected under a stereomicroscope, and categorized according to measurements and morphological characteristics. Infection rates and intensities were then calculated. A total of 8 Echinostoma hortense metacercariae collected in gobies from Jido-myeon in Shinan-gun were used to experimentally infect a rat to obtain adult worms. Two weeks after the infection, 4 adult flukes were recovered from the small intestine of the rat, which were fixed in 10% neutral buffered formalin, and stained with Semichon's acetocarmine in order to observe their morphological characteristics.Metacercariae of H. nocens, H. continua, and Stictodora spp. were detected in all of 15 gobies caught from Aphae-myeon in Shinangun. The average numbers of metacercariae per infected fish were 153 (H. nocens), 20 (H. continua), and 334 (Stictodora spp.) respectively. A total of 11 P. summa metacercariae were collected in only 1 goby from Aphae-myeon (Table 2). In 2 of 14 gobies Echinostoma hortense and Heterophyid Metacercariae Encysted in Yellowfin Goby, Acanthogobius flavimanus, from Shinan-gun and Muan-gun (Jeollanam-do), Korea Korean J Parasitol. Vol. 47, No. 3: 307-310, September 2009 DOI: 10.3347/kjp.2009