Students' poor performances of Physical Sciences are a major problem in South Africa, particularly the district of Motheo. Even though the Department of Elementary Education in South Africa has invested a great deal of money for Physical Sciences in the new curriculum called the Curriculum Assessment Policy Statement (CAPS) to train teachers through workshops and in-service education, students have not still been well performing for this subject. Studies have been conducted on reasons and possible solutions/treatments of students' poor performances in Physical Sciences, but little progression has been achieved yet. This study aimed at comparing the teachers and students' perceptions of the factors contributing to poor performance in Physical Science, and discussing how to improve such performance. The sample of the current study consisted of seventy nine grade 11 students and seven teachers selected via convenient sampling method. Within a quantitative research method, a survey research design was used. The teachers' and students' responses to the questionnaire were compared to find out whether they have similar perceptions of the factors contributing to poor performance in Physical Sciences. This study revealed that they had varied perceptions of the factors under investigation. For example; teachers regarded instructional language (English) and students' poor mathematical backgrounds as great contributors to students' poor performances, whereas students saw a lack of practical work as a great contributor to their poor performances in Physical Sciences. The teachers and students also suggested different ways on how to improve students' performances in Physical Sciences.