Majority of the students regarded algebra as one of the difficult areas in mathematics. They even find difficulties in algebraic expressions. Thus, this investigation was conducted to identify common errors in algebraic expressions of the preservice teachers. A descriptive method of research was used to address the problems. The data were gathered using the developed test administered to the 79 preservice teachers. Statistical tools such as frequency, percent, and mean percentage error were utilized to address the present problems. Results show that performance in algebraic expressions of the preservice teachers is average. However, performance in classifying polynomials and translating mathematical phrases into symbols was very low and low, respectively. Furthermore, the study indicates that preservice teachers were unable to classify polynomials in parenthesis. Likewise, they are confused of the signs in adding and subtracting polynomials. Results disclosed that preservice teachers have difficulties in classifying polynomials according to the degree and polynomials in parenthesis. They also have difficulties in translating mathematical phrases into symbols. Thus, mathematics teachers should strengthen instruction on these topics. Mathematics teachers handling the subject are also encouraged to develop learning exercises that will develop the mastery level of the students.