Psittacosis-ornithosis-chlamydiosis is a bacterial zoonosis caused by Chlamydophila psittaci. The animal reservoir consists of all birds, most of which are asymptomatic carriers. In humans who become infected through contact with birds, the disease presents as a flu-like syndrome accompanied by pneumonia. Little data on this disease is available in France. A descriptive study was conducted in 2008–2009 by the French Institute for Public Health Surveillance, the French Agency for Food Safety, and the National Reference Center to estimate the incidence of hospitalized cases, detect clusters of cases, and assess the relevance of implementing surveillance for this disease. Investigations of clusters of cases led to the implementation of recommendations for collective and individual prevention. The results of veterinary investigations allowed for the formulation of hypotheses regarding the transmission of the bacterium from animals to humans. Above all, the study demonstrated the importance of joint surveillance of animal and human cases. In most situations, the detection of human cases makes it possible to detect the animal infection. Close collaboration between human and animal health stakeholders is therefore necessary to strengthen the fight against this zoonosis and implement management and prevention measures, particularly among those most at risk. (R.A.)