Among the key areas focused in the science teacher education literature, understanding and challenging the teachers' knowledge about Nature of Science (NOS) is considered as an urgent need of the time in order to bring change in science teaching and learning processes. Researches also show that teachers' personal theories about NOS have a great influence on what they do in classrooms. Thus, understanding teachers' views about NOS is important and this has also been identified as an area of research in the Pakistani context (Halai, 2004). Therefore, this study aimed to assess high school Pakistani science teachers' conceptions about NOS and whether these conceptions were related to selected demographic variables. These variables include: (i) participants' gender, (ii) years of teaching experience, (iii) academic qualification, (iv) professional qualification, and (v) system of school. A cross-sectional survey study was carried out. A multistage cluster sampling technique was used to recruit 147 science teachers from government (n= 21) and private (n= 20) schools of three towns of Karachi. A modified version of 14-item "Views on Science- Technology-Society" (VOSTS) questionnaire was administered to asses participant teachers' views of certain aspects of NOS. Participants' responses were categorized as "naive", "have merit", or "informed". The questionnaire was piloted before administering it to the147 participant teachers. The response rate was 100 percent. The results showed that a majority of participants held naive views of a majority (n=10 items; 71%) of the target NOS aspects. Furthermore, teachers views on some aspects of NOS were found to be related with some of the selected demographic and background variables. These include participants' gender, years of teaching experience, professional qualification and system of school. The study provides insight into an under-researched area of teachers' perception about NOS in a developing country by using VOSTS, a questionnaire adapted as part of the current research. The findings of this study will contribute to the literature on NOS in the Pakistani and other contexts as well. The results might be useful for professional development institutes in designing training programmes for science teachers to provide them better understanding about an important aspect of science-NOS.