The purpose of this research is to analyze the effect of GeoGebra in three-dimensional geometry learning on students 'mathematical communication ability as a whole and based on students' prior mathematical abilities. This quasi-experimental research with randomized posttest only design included 84 XII grade students in high school in Central Jakarta, Indonesia. Before the research, students were grouped based on their prior mathematical abilities including high, medium and low groups. The research data were the results of mathematical communication skills tests consisting of 7 questions which were then analyzed by Mann- Whitney test. The results reveal that overall and for students with high and medium mathematical prior abilities, there were significant differences in mathematical communication skills between students who received GeoGebra assisted Geometry learning and students who obtained conventional mathematics learning, while for students with low prior mathematical ability, there is no significant difference.