Pulmonary agenesis is defined as the complete absence of one or both lungs, including the bronchi, bronchioles, vasculature and lung parenchyma. Most of these malformations are detected in early childhood. A residual number remains asymptomatic and undiagnosed until adulthood. The clinical presentation is wide, ranging from asymptomatic to respiratory complaints like dyspnoea, respiratory distress and a history of recurrent lung infections. This case presents a 54-year-old woman with complaints of coughing, dyspnoea for medium exertion and wheezing for a couple of months. Based on the results of complementary diagnosis methods, right pulmonary agenesis was diagnosed without other malformations. Simultaneously, an asthma diagnosis was also performed. The treatment of pulmonary agenesis is symptomatic. Simultaneous cardiovascular malformations could require surgical interventions. This case demonstrates that pulmonary agenesis may remain undiagnosed, be identified incidentally, and have a good and long prognosis.