Language of instruction, both in schools and higher education institutions (HEIs), is a contentious issue in South Africa. At our university in the KwaZulu-Natal province of South Africa a language policy was approved in agreement with the Language Policy for Higher Education, recommending promotion of isiZulu as a medium of instruction for teaching and learning. In complying with this policy the School of Education of our university offered three education modules (Numeracy, Life Skills and Literacy) in the Foundation Phase (FP) Postgraduate Certificate in Education (PGCE) through the medium of isiZulu. Against this background we conducted a qualitative study with 16 FP PGCE pre-service teachers selected purposefully from the 2011 cohort who completed the FP numeracy education module in isiZulu. Participants were generally positive about their experiences of being taught in isiZulu, but highlighted challenges related to isiZulu as a medium of instruction for academic concept explanations, translation of teaching and learning materials, and the status of isiZulu as an instruction medium at a HEI.