The grade 12 pass rate in mathematics is of national concern in South Africa. This pass rate is influenced by the quality of teachers with which the learners are faced. In this paper we report on the level of understanding of content by grade 12 mathematics teachers. We specifically studied their performance in grade 12 assessment tasks in trigonometry, functions and calculus. The sample (n=28) of teachers was selected by the mathematics subject advisor of a district in KwaZulu-Natal, South Africa. The teachers were informed that on the fifth day after the first session they would write a test based on grade 12 mathematics examination type questions on functions, trigonometry and calculus. That test of one-hour duration was set and marked by the subject advisor. The results for the overall test and for each of the three sections were analysed to determine the mean, standard deviation, minimum score, range, first and third quartiles and to produce histograms. We found that fifty percent of the teachers attained scores of less than 57% in assessment tasks based on trigonometry, functions and calculus. We argued that these low scores of the teachers who are expected to teach the relevant content, could be a contributing factor to the low pass rates by grade 12 learners in the National Senior Certificate Examinations