Chlamydophila psittaci is a Gram negative, coccoid, obligate intracellular bacterium that is endemic worldwide. The organism is well adapted to avian hosts and readily causes clinical disease known a psittacosis or ornithosis. This first part of this article summarizes current knowledge on avian chlamydophilosis with emphasis on clinical signs, lesions, and pathogenesis as they pertain to the case of "Sinbad", a one year old green winged Macaw that presented to Cornell University with a history of chronic weight loss and failure to wean. The second part of the article emphasizes the difficult task of diagnosing psittacosis. In particular, a confirmed case of Chlamydophila is defined on the basis of at least one of the following laboratory results: 1) isolation of C. psittaci in culture, 2) fluorescent antibody staining to identify chlamydophila antigens, 3) serologic titers, 4) identification of Chlamydophila inclusion bodies within macrophages of smears stained with Gimenez, Macchiavellos, or Pierce Vander Kamp stains. The advantages and disadvantages to these laboratory techniques are discussed in detail along with the treatment options and zoonotic potential. It is concluded that the diagnosis of Chlamydophilosis is laborious and that there is a definite need for more accurate and simplified diagnostic tools in both organism and antigen/antibody detection.