Recent reforms in mathematics education have increased the need for teachers to attend professional development programs. In order to motivate teachers to attend such programs and to maximize their effect on teachers' development, we believe it is important to adapt the contents of such programs to teachers' perceived needs. The current study was designed to explore the professional needs of Israeli mathematics teachers, as they perceived them. Our results show that teachers are mainly concerned with developing their mathematical knowledge and acquiring knowledge that relates to the way in which students comprehend various mathematical concepts. However, these concerns stem from different positions that can be attributed to their teaching experience: new teachers appear to be self-centered; therefore their concern with developing their knowledge might be a result of a need to gain self-confidence. More experienced teachers are able to consider the effect of their teaching on students' learning, and it appears that their wish to acquire knowledge stems from this perspective. Highly experienced teachers, like new teachers, are also self-centered, believing they know everything about teaching and learning, and therefore express interest in acquiring knowledge merely for satisfying their own curiosity. (Contains 3 notes, 2 tables, and 1 figure.)