Background: Perinatal Hepatitis C Virus (HCV) transmission occurs in 4–7% of the cases with detectable viremia at delivery. HCV testing in pregnancy is recommended. The fetal infection was previously described as asymptomatic although there are two cases, including this one, to report the presence of isolated fetal ascites in HCV infected fetuses. Case report: A 42-year-old patient, 3G, 3P, presented in the Emergency Room for painful uterine contraction. The third-trimester ultrasound examination noted severe fetal ascites, accompanied by hyperechoic bowels and polyhydramnios. The diagnosis required a detailed ultrasound exam, invasive testing (amniocentesis, cordocentesis, and fetal paracentesis), and a complete workup. The mother tested positive for HCV antibodies, and the fetal cord blood tested positive for HCV RNA. The ascites resolved after paracentesis, and the gastrointestinal and respiratory functions markedly improved. The fetus was delivered at term in good condition. Conclusions: The etiology of isolated fetal ascites is broad. This case may indicate that intrauterine HCV transmission is a potential cause of isolated fetal ascites in the absence of other explanation, and isolated fetal ascites can be the only sign revealed on a routine examination. We suspected, having no other detected cause for ascites, the intrauterine transmission of HCV. Invasive procedures, such as paracentesis, are required for abdominal decompression to manage isolated fetal ascites, as it may be a saving procedure. A genetic investigation is needed, and a good neonatal outcome is expected in the absence of fetal structural or genetic abnormalities, as in our case.