A number of authors have recognized the importance of understanding the nature of science for scientific literacy. Different instructional strategies such as decontextualized, hands-on inquiry, and history of science activities have been proposed for teaching NOS. This article seeks to understand the contribution of HOS in enhancing biology teachers’ understanding of NOS, and their perceptions about using HOS to teach NOS. These teachers, enrolled in a professional development program in Chile are, according to the national curriculum, expected to teach NOS, (...) but have no specific NOS and HOS training. Teachers’ views of NOS were assessed using the VNOS-D+ questionnaire at the beginning and at the end of two modules about science instruction and NOS. Both the pre- and the post-test were accompanied by interviews, and in the second session we collected information about teachers’ perceptions of which interventions had been more significant in changing their views on NOS. Finally, the teachers also had to prepare a lesson plan for teaching NOS that included HOS. Some of the most important study results were: significant improvements were observed in teachers’ understanding of NOS, although they assigned different levels of importance to HOS in these improvements; and although the teachers improved their understanding of NOS, most had difficulties in planning lessons about NOS and articulating historical episodes that incorporated NOS. The relationship between teachers’ improved understanding of NOS and their instructional NOS skills is also discussed. (shrink)