Pulmonary agenesis is a rare congenital anomaly, estimated to complicate around 1 per 15,000 pregnancies, in which there is complete absence or severe hypoplasia of one or both lungs, frequently associated with other abnormalities. A prospective prenatal diagnosis is a challenge, and a substantial proportion of cases are diagnosed by fetal magnetic resonance imaging, postnatal computed tomography, or postmortem. Thus, there are only a few reported cases of prenatal diagnosis in the literature. We report the prenatal diagnosis of isolated right lung agenesis diagnosed with sonography alone at a relatively early gestational age. We also present a systematic review of the literature for this condition to accompany this case study.