The authors describe a case of toxoplasmosis occurring in a subject who is HIV positive who presented with a cough and an infectious syndrome. Toxoplasma gondii was identified in the broncho-alveolar lavage even though the X-ray, the fibroscopy, blood gases and the broncho-alveolar lavage were normal. The frequency of pulmonary disease in the course of a toxoplasma infection in HIV subjects was underlined. Amongst the non invasive diagnostic methods the authors stress the value of broncho-alveolar lavage with a close search for toxoplasma even in the absence of any suggestive paraclinical anomalies.