This study was conducted at Bagabaga College of Education, Tamale. Its purpose was to find out the Pedagogical Content Knowledge exhibited by science teacher trainees in their teaching practices and how it influenced their teaching of science. Qualitative (descriptive) research design was used for this study. The research targeted the third year science teacher trainees on their internship programme. Stratified sampling was used to get the science teacher trainees across the three districts of the partner schools and simple random sampling was used to select 21 participants (Science Teacher Trainees) for this study.The instrument used to collect data in this research was observation schedule. Observation checklist was used to track the pedagogical content knowledge of the science teacher trainees and its influence on their science teaching. The study found that Science Teacher Trainees had developed pedagogical content knowledge; knowledge of learners, knowledge of curriculum, knowledge of content and knowledge of pedagogy. The observation conducted on the science teacher trainees’ works revealed that the pedagogical content knowledge had a significant influence on their teaching

Keywords : PCK; Content Knowledge; Pedagogical Knowledge; Knowledge of learners; science student teachers;