In response to a Quality Assurance trial held in the United Kingdom where laboratories incorrectly identified a bloodstain pattern prepared by coughing blood and to offer an increased awareness to laboratory staff when encountering such patterns in the course of their work, this article provides a brief definition of expirated blood, as well as a review of the literature available on expirated blood. Explanations were provided on how any injury or medical condition resulting in blood entering the respiratory system could be a source of expirated blood, such as injuries to the mouth, nose, and oral cavity or head injuries causing internal bleeding and entering the back of the nasal cavity. In addition, expirated blood could also be mixed with saliva, mucus, lung surfactant, or cerebrospinal fluid and thereby, appear diluted. Finally, bloodstain patterns from expirated blood can vary tremendously in appearance and be affected by factors affecting any bloodstain pattern. Based on the circumstances of the case, the possibility of expirated blood should always be considered. Figures