The role of health technology assessment (HTA) in low- and middle-income countries (LMICs) has become increasingly important in order to inform resource allocation and wider health policy decision-making. Using the case study of Tunisia’s first published HTA on trastuzumab in early and locally advanced HER2 positive breast cancer, we aim to evaluate how the key principles and elements of HTA might be applied in the assessment of health interventions undertaken by emerging HTA agencies in LMICs, in light of likely capacity and resource constraints. We critically evaluate the Tunisian HTA in the context of widely cited ‘best practice’ guidelines to determine how the assessment conducted by the Tunisian National Authority for Assessment and Accreditation in Healthcare aligns with recommended HTA methods. We find the Tunisian trastuzumab HTA to be an encouraging example of the ability of a newly established agency to conduct a transparent and scientifically rigorous evidence driven assessment. We draw on lessons learned in other countries and present a number of ongoing research and policy initiatives to promote the implementation of HTA, given resource constraints; in order to formulate recommendations for future HTA practice in Tunisia and LMICs, respectively. We discuss the sharing of evidence and resources and the potential of stakeholder engagement in building and strengthening HTA capacity worldwide.