This paper presents the results of a project which aims to investigate mathematics teaching knowledge of preservice Turkish mathematics teachers. The study focuses on a particular subject area of mathematics, algebra. The research was conducted with 1146 participants sampled from 18 state universities. Released items of TEDS-M were used as data collection tool. TEDS-M assessment framework was adapted for this study to be able to make comparisons with international averages. As a result we concluded that Turkish future teachers performed better in applying cognitive domain compared with reasoning. We also observed incapable of participants providing a formal proof similar with original TEDS-M countries.