The study's purpose was to describe selected laryngeal activity of brass-wind players during the performance of selected musical exercises. Research problems included the observation and description of three internal areas of activity of ten trumpeters as they performed each exercise. Specific areas of observation were 1) movement of the epiglottis during the performance of each exercise, 2) movement of the vocal folds/arytenoid cartilage which includes changes in the size of the glottis during the performance of each prescribed exercise, and 3) movement of the thyroid cartilage during the performance of each prescribed exercise. Musical exercises performed by each of the subjects included a sound volume change, use of vibrato, single-tonguing, step-wise descending and ascending slurs, descending and ascending lip slurs, register change, and a descending chromatic scale. In addition, each subject performed an excerpt from the second movement of the Haydn Trumpet Concerto. Data were collected through direct observation of subject performances and then described using three different means. Data analyses revealed a prominent amount of highly individual, non-patterned laryngeal activity which played an integral role in the performance of each subject. Individuals including Law (1960), Cramer (1955), Jacobs (Stewart, 1987), and Noble (1964) have advocated an unrestricted airway during brass performance. Contrary to this advice, findings in the present study indicate that a great deal of varying, involuntary restriction is present in the laryngeal area during performance. Further, such activity appears necessary to brass performance. Others, including Farkas (1962), Schuller (1962), and Wick (1971) , have endorsed conscious use of the glottis during brass performance. While findings in the present study imply that there is a presence of voluntary or reflexive glottal activity during brass performance, evidence does not support any theory which suggests conscious use of the laryngeal mechanism.