The purpose of the study was to understand competencies needed by teachers of students with hearing impairments in Taiwan and to explore if courses offered by preservice training institutions matched those competencies. The researcher used a questionnaire to ask opinions on professional competencies need for 398 teachers who taught students with hearing impairments at different school settings across various levels. Results showed the following findings: (1) All teachers of students with hearing impairments perceived that the most important competencies are: dealing with students' problem behaviors, treating students fairly, applying various instructional methods vividly, arranging activities based on students' developmental needs, facilitating students' independent communication skills, guiding students to build up positive self concept, conducting classroom management effectively, assessing students' placement appropriately, and assessing students' verbal abilities. (2) Teachers who taught at different levels held significant different opinions on most categories of competencies. (3) Teachers who taught at different placement settings existed significant different opinions on most categories of competencies. (4) Deaf-school teachers who taught at different school age levels held significant different opinions on most categories of competencies. (5) Teachers of resource rooms and special classes who taught at different school levels held significant different opinions on most categories of competencies. (6) Elementary school-level teachers who taught at different placements held same opinions on most categories of competencies. (7) Junior-high school-level teachers who taught at different placements held same opinions on most categories of competencies. (8) There was no interaction effect of different levels and different placements on teachers' competencies. (9) The background information variables had no significant different effect on teachers' competencies. (10) The courses offered by preservice teacher preparation universities/colleges could meet most competencies requirements; yet it is necessary to offer more new courses in the future.