Pulmonary agenesis is a very rare condition and many of them are associated with a variety of cardiac and non-cardiac malformations. We report an eight-month old girl with chronic lung infection due to right sided pulmonary agenesis without any associated major cardiac or non-cardiac abnormalities. The case brings in forth the importance of investigating any infant presenting with features of chronic lung infection for any congenital abnormality of the lung including aplasia of the lung. This case also emphasizes that mildness of the attack does not exclude right sided aplasia of the lung.