Trigonometry has been recognized as an area of weakness amongst Irish second-level students and has been deemed a major negative influence on Irish students’ progression and success in tertiary mathematics. This is also an international issue. One cause of this problem cited in the literature is poor teaching of the topic. Subject Matter Knowledge (SMK) has been identified as one of the most important components of a teacher’s skill set. The authors conducted a multi-phase research project, however this presentation will only focus on the assessment phase of the research. A 16 item trigonometry assessment was developed in this research that examined trigonometric concepts from primary level up to the end of secondary level. This presentation discusses the findings from the evaluation of this assessment after it was administered to a sample of 50 pre-service secondary level mathematics teachers at an Irish university. The study showed that the sample has gaps in their understanding of secondary level trigonometry and have a level of SMK that only allows them to teach the early years of secondary trigonometry in a relational way. The implications of the findings on teacher education are discussed.