**Abstract**

Learners in the Eastern Cape Province have over the years performed poorly in the National Senior Certificate Mathematics examinations. This study sought to investigate the determinants of under-performance of Grade 12 learners in Mathematics. The study adopted a qualitative case study in which data were gathered through interviews with teachers and learners. The purposely selected sample comprised three teachers and nine learners from the same school. The findings showed factors that have a direct influence on teaching strategies such as the inadequacy of resources and under-qualified teachers. The other factors associated with learners were learners' attitudes and general understatement of the subject contributing to undesirable results. Recommendations, as well as suggestions for further research aimed at addressing the factors identified, are advanced.

**Keywords:** determinants, Mathematics, under-performance, Grade 12 learners, Mathematics teaching strategies
