The purpose of this study was to investigate the effects of using 3-D virtual environments and concrete manipulatives on spatial visualisation and mental rotation abilities. A 3-D virtual unit block simulation was designed with True Vision 3D game engine. The study was implemented at two schools with 108 students from fifth grade. A quasi-experimental pre-test post-test research design was followed at each school. The 3-D virtual environment was used in the experimental groups. Unit blocks were used as concrete manipulatives in the control groups. Spatial Visualisation and Mental Rotation Tests were administered before and after the implementations. Spatial Visualisation and Mental Rotation Test scores increased significantly in the control group. Spatial Visualisation Test score increased significantly in the experimental group, while the increase in Mental Rotation Test score was not statistically significant. There was no significant difference between the groups in terms of Spatial Visualisation and Mental Rotation Test results.