Psittacosis, also known as ornithosis, is a disease caused by Chlamydia psittaci. The most common clinical presentation is insidious onset, mild symptoms resembling a nonspecific viral illness and preference for the lungs. It is rarely a systemic and fatal disease. It is described a rare case of pneumonia due to Chlamydia psittaci that progressively developed into respiratory failure, requiring mechanical ventilation. It is very important to consider psittacosis in cases of atypical pneumonia whose evolution is unsatisfactory, with no response to antimicrobial therapy and epidemiology is positive for exposure to birds. Prompt recognition is vital as the response to appropriate treatment is excellent. Delayed diagnosis may lead to a severe course and fatal outcome.

Keywords: Mycoplasma pneumonia. Ornithosis.