Mathematics is seen as the bedrock for scientific, technological and economic advancement of any country. The study explored the perceived causes of low academic performance of Senior High School students in core mathematics in the Kumasi Metropolis of Ghana. The study used the descriptive survey design with quantitative approach. Multi-stage sampling procedures were used to select a sample of 431 respondents (381 students and 50 core mathematics teachers). Students and teachers’ questionnaires were used to collect data for the study. Means and standard deviations were used to analyse the data that was gathered. The findings of the study revealed that school-environment, teachers and students’ factors such as inadequate teaching and learning materials, lateness and absenteeism, inability of teachers to complete their syllabus, students being unhappy in core mathematics classes and poor attitudes toward core mathematics as contributors to the low performance in core mathematics. Among others, recommendations were made based on enforcing the necessary laws by stakeholders in education to curb lateness and absenteeism, provision of TLMs and exhibition of good attitudes towards core mathematics.