This study investigated arthropod and nonarthropod sources of reported bites and itching in a word processing division of a St. Louis, Mo., municipal department. Bird and rodent mites were suspected as causes of the bites because of the large population of pigeons around window ledges on some floors and the sighting of mice in the office. No mites or other arthropods were found to be responsible for the problem. Air samples were negative for fiber glass. Surface-vacuum samples collected around desks contained small quantities or traces of fiber glass or mineral wool. Humidity in the occupied space was considered low, about 35% relative humidity, with carbon dioxide measurements exceeding 1000 ppm. A single cause of the bites was not identified; however, a combination of surface-borne dust on desk tops and floors, the presence of minute quantities of mineral wool and fiber glass, relatively dry conditions, little or no outdoor air supplied to the work space, evidence of seasonally associated high work load, labor/management strife, and the presence of over 17 computers being used on a 24-hour basis (possibly leading to high levels of static electricity) were suspected as multiple causes of most of the “bites.” After removal of loose mineral wool and dirt from an air handling unit and implementation of an aggressive cleaning routine, no more bites or itching were reported after a 6-month, 1- and 2-year follow-up period. Further research is needed to determine the relative importance of surface-borne dust and fibers, work stress, psychosocial support, and static electric fields, to produce bitelike sensations.