Secondary school teachers in Tanzania have been attempting to implement the inquiry-based science curriculum since 2005. This study is descriptive and was designed within the realms of a Type IV case-study design (Yin, R. K. 2014. "Case study research: Design and methods" 5th ed. SAGE) to investigate their concerns in dealing with this curriculum. It employed the Concern-Based Adoption Model (CBAM) as its lens and collected data using the Stage of Concern (SoC) questionnaire. In addition, the study used background information of the participants themselves and their context collected using one-on-one interviews to enrich the interpretation of revealed concerns. The findings revealed variations in the nature and intensities of concerns amongst science teachers in the case-study schools. These variations were partly due to the differences in contextual and background characteristics of staff of the three case-study schools. The implications of these findings for both policy and practice are discussed.