Objective: Jacobsen syndrome is an infrequent contiguous gene syndrome that involves the deletion of the long arm of chromosome 11. It is mostly accompanied by intellectual disability and other abnormalities. The majority of the patients are hospitalized or lost within the first two years of life. Case: We report a case of a fetus at 21 weeks of gestation with Jacobsen syndrome who presented with a conotruncal cardiac defect. Amniocentesis was performed, and karyotype analysis revealed that there was a de novo deletion of chromosome 11. The family decided to ter- minate the pregnancy. Conclusion: Prenatal diagnosis of Jacobsen syndrome is not always possible, since the characteristic ultrasound findings vary greatly between patients. Additionally, existing symptoms and signs may not always be found with imaging techniques. However, if present, certain ultrasonographic findings should lead clinicians to consider the syndrome. The study aims to present a rare case of Jacobsen syndrome, inform the clinicians, and guide on this syndrome and its possible outcomes.