Fetal ascites is an uncommon abnormality usually reported in relation to non- immunological causes. The prospect for fetal and neonatal mortality is high, particularly when the ascites develops before 24 weeks of gestation. The diminution of severe fetal ascites without intrauterine management, especially with an uncomplicated neonatal outcome, is unusual. We report a case of isolated fetal ascites detected at 20 weeks' gestation. All investigations carried out were normal. Consecutive ultrasound examination showed ascites at 20 weeks' gestation. A follow-up ultrasound examination at 6 months of age revealed complete recovery from the ascites. Spontaneous resolution of fetal ascites, with a good prognosis, can occur in cases with an idiopathic aetiology.