The main purpose of this study is to determine the effects of using dynamic mathematics software on pre-service mathematics teachers' ability to infer the shape of a cross section of a three-dimensional solid, as well as on their spatial visualization skills. The study employed a quasi-experimental design with a control group; the Purdue Spatial Visualization Test (PSVT) and Santa Barbara Solid Test (SBST) were applied as pre- and post-tests. There were 48 students in the experimental group and 49 students in the control group. While the students in the experimental group took a course in a computer laboratory, the control group took the same course in their regular classroom. The results of the study showed that using dynamic mathematics software had a positive effect on pre- service mathematics teachers' ability to infer the cross section of three-dimensional solids and on their spatial visualization skills.