This article describes a part of a large scale study which helped to gain understanding of the high school mathematics teachers' perceptions related to the integration of history of mathematics into instruction. There is obvious lack of correspondence between general perception about possible benefits of students learning the history of mathematics and teachers' perceptions of the integration of the history of mathematics in curriculum. A total of 367 mathematics teachers from one of the New England states, USA, participated in an on-line comprehensive survey, which was designed by the researchers. We report on several factors that affect teachers' decision whether include history of mathematics into curriculum, offer some recommendations for teacher professional development and suggestions for further research.