A Graphing Calculator (GC) is one of the most portable and affordable technology in mathematics education. It quickens the mechanical procedure in solving mathematical problems and creates a highly interactive learning environment, which makes learning a seemingly difficult subject, easy. Since research on the use of GCs for the teaching and learning of probability in institutions of higher learning appears to be limited, a study was conducted to examine the effects of the use of GCs on students' performance in probability. The study involved 65 pre-university students in a private institution of higher learning in Malaysia. Hypothesis testing showed that there is a significant difference in the mean score of the post achievement test between the experimental and control groups. Students in the experimental group displayed higher achievement than their peers in the control group in the Probability Achievement Test (PAT). Findings also showed that the use of GCs benefits students of all levels, that is, high, average and low mathematics achievers. Qualitative data provides a more lucid picture of how GCs aid in improving understanding and performance. Recommendations made will provide researchers, policy-makers and educators an alternative means of enhancing the quality of probability education. (Contains 3 tables and 6 figures.)