Hydrops fetalis is defined as the accumulation of fluid with or without edema involving at least two fetal components. About 10% of cases are due to maternal hemolytic antibodies, that is, immune hydrops, while 90% of cases are nonimmune. Nonimmune hydrops fetalis (NIHF) is a heterogeneous condition that may be secondary to over 100 conditions, the cardiovascular causes are the most common. A significant percentage of cases will still not have an identifiable cause even after postnatal evaluation. Sonographic features include increased amniotic fluid volume, increased nuchal translucency, placentomegaly, fetal pleural or pericardial effusion, generalized fetal body swelling, and umbilical venous dilatation. Once the diagnosis of NIHF has been established, scans should be performed every 2–3 weeks to monitor the evolution of hydrops, and every effort should be made to identify the underlying cause. The treatment of nonimmune hydrops is determined by the gestational age (GA) at which the diagnosis is made, as well as the ability to identify the cause of the NIHF. Delivery should be done at a tertiary care hospital for appropriate neonatal interventions. Timing and method of delivery depend on the cause of hydrops. Preterm delivery is recommended only for obstetric indications including the development of “mirror syndrome.” The prognosis is dependent on the underlying cause and onset of NIHF. Progressive unexplained hydrops is often lethal before or soon after birth with an overall mortality of 50–90%. NIHF secondary to treatable causes such as fetal arrhythmia, chylothorax, or infection with parvovirus B19 has a better survival rate.