Although Inquiry-Based Science Teaching (IBST) and the Nature of Science (NOS) are well documented as important aspects of teaching science subjects in schools, little research has been undertaken to understand how these aspects feature in secondary school science curricula in Tanzania. Thus, this study examined the extent to which IBST and NOS are featured in secondary school curriculum documents for science subjects. In addition, the challenges facing the integration of IBST and NOS in science teaching in Tanzanian secondary schools are highlighted. By analysing five curriculum documents and the Basic Education Statistics in Tanzania, the study established that IBST and NOS are neither formally recognised as important aspects of science education, nor given due attention in curriculum documents. Moreover, a lack of coherence among various elements of the curriculum, which can affect the integration of IBST and NOS, was observed. Finally, it was established that several challenges such as larger class sizes, insufficient time allocation and overemphasis on content coverage need to be addressed so that IBST and NOS could be fully integrated into science teaching in Tanzania. The study does not only highlight the theoretical trends related to IBST and NOS, but also discusses their theoretical and practical implications for science teaching