This is a study of Irish student teachers' subject knowledge in mathematics using a mathematics subject audit instrument developed by researchers in England. A cohort of Bachelor of Education and Post Graduate Diploma in Education students took the audit and their mathematical knowledge profiles are compared, together with their mathematics results in the Leaving Certificate examination and whether the students had studied mathematics post Leaving Certificate. Strengths and weaknesses in mathematical subject knowledge for primary teaching are inferred from the findings of the audit and implications of these for mathematics education of pre-service primary teachers are raised. Each of the sixteen audit items has been matched with a five point scale to assess student self confidence in approaching the test item and a five point scale to indicate student opinion of the relevance of the knowledge examined by each item to the Irish primary mathematics curriculum. The study also investigates the relationship between student confidence in answering a particular mathematics question, competence in providing a satisfactory solution and perceived relevance to the primary school curriculum.