The goal of this study was to determine the mathematics achievement level in basic numeracy and algebra concepts of students in a two-year program in a technical vocational school of higher education and determine the errors that they make in these topics. The researcher developed a diagnostic mathematics achievement test related to numeracy and basic algebra concepts by determining the common errors in numeracy and algebra through a review of the literature. The 20-question test was administered to 130 students who were continuing their education in industrial electronic and electronic communication programs of a technical vocational school of higher education in a middle sized university in the western part of Turkey. The mean students' achievement level of mathematics was 6.31, which was a quite low score, out of a possible 20 points. The results of the study point out that there is a lack of understanding of the concepts of numbers and algebra. Analysis of the errors that students exhibit provide a valuable insight in to the nature of mathematics learning that many vocational education students have carried with them into higher education from their earlier learning experiences.