The nature of science (NOS) is an important area in teaching and learning science. Teachers’ conceptions of the NOS have a direct influence on their classroom teaching and thus influencing the students’ conceptions. Therefore, “exploring teachers’ conceptions about the NOS” is considered as one of the important areas of research in science teaching and learning process. This study aims to investigate secondary science teachers’ conceptions about four selected aspects of NOS, which are, empirical nature of science, tentativeness, scientific theories and laws and scientific method. It was a qualitative exploratory study and conducted in a private school in Karachi on a sample of three science teachers. Data was collected using a questionnaire, interviews and classroom observations. Two types of research tools, Views of Nature Of Science (VoNOS) and Nature Of Science Research Protocol (NOSRP) were employed to collect data. For data analysis each participant was considered as a separate case and data obtained through questionnaires, interviews and classroom observations were used to develop three separate cases. These cases are cross cased to compare and contrast the three participants’ views about four selected aspects of NOS. The findings revealed that teachers possessed mixed views about the empirical NOS and tentative NOS. Similarly, these teachers possessed inadequate conceptions about scientific theories and laws and scientific method. Furthermore, it also became evident that teachers did not translate their NOS conceptions in their classroom teaching in an explicit way. Their teaching, however, sometimes reflected NOS teaching in an embedded form. These findings have implications as they may provide practical and contextual information about teachers’ conceptions and their classroom practices related to NOS. The findings may help teacher educators and professional organizations in designing science teacher programs that may address the component of NOS.