© 2011 Logos Medical Publishing . All Rights Reserved.Urachal cysts are rare in infants and usually asymptomatic. They may present with clinical manifestations when became infected. Ultrasonography (USG) and computed tomography are considered to be the best diagnostic procedures. A case of infected urachal cyst with a presumptive diagnosis of incarcerated umbilical hernia, is presented to evaluate the clinical findings and differential diagnosis of urachal cysts. A 2.5 month-old male infant admitted to our department with complaints of irritability, fever, umbilical bulging and periumbilical erythema. US evaluation is reported as incarcerated umbilical hernia. During exploration an urachal cyst was found and total excision was performed. The postoperative course was uneventful. Infected urachal cysts may cause clinical findings resembling those of incarcerated umbilical hernias. Infected urachal cysts should be kept in mind in infants presenting with umbilical hyperemia, erythema and tenderness, so as to establish accurate diagnosis and treatment.