Introduction: The pneumocystosis is an infection caused by a saprophytic germ Pneumocystis jiroveci. It is exceptional in immunocompetent patients. Case report: This is a 30-year-old patient, admitted to the service for an acute respiratory failure. She was treated for pulmonary tuberculosis 6 months ago. The review has objectified clinique cyanosis of the lips and extremities with a blood pressure 120/70 mmHg, a heart rate of 70 bats/min, a temperature of 38°C and SaO₂ to 82% in the open air. The chest radiograph objectified reticulonodular opacities on the right. The patient was put under bi-broad-spectrum antibiotics. Due to the non improvement of the patient’s state, the search for Pneumocystis jiroveci in induced sputum was made and it was positive. The search for a field of immunosuppression was negative.