Breeder squab candidates between the ages of 6 and 16 wk were submitted to the California Animal Health and Food Safety Laboratory, Turlock branch, as a result of respiratory distress and increased mortality. These Cases were submitted from one Northern California commercial squab operation on three separate occasions occurring between December 2007 and March 2008. Severe trichomoniasis was identified, primarily in the tracheal epithelium and lung of squabs, with few or no lesions in the oral cavity, crop, esophagus, and livers, where the organism commonly infiltrates. Infiltration of the trachea and lung sections with trichomonads was associated with a severe inflammatory response in the surrounding tissue. Diagnosis was confirmed with the use of histopathology and an immunoperoxidase special stain. Oxytetracycline supportive antibiotic therapy to prevent secondary bacterial infections was administered to remaining squabs on the farm, but no specific treatment Regimen was instituted. This novel respiratory presentation of trichomoniasis continued over a period of 3 mo, until mortality gradually returned to normal.