Fiber-reinforced composite materials have many advantages in various engineering applications when compared to traditional materials such as glass, metals, ceramics and unreinforced plastics. Recently, textile-reinforced composites are increasingly used in various industries including aerospace, construction and automotive. This study aims to investigate the geometric characteristics of three-dimensional (3D) woven preforms which are used as reinforcement materials in composites. To this end, 3D woven preforms with three different weave types were produced namely 3D orthogonal, 3D plain z-orthogonal and 3D satin z-orthogonal. The effect of weave pattern and the number of layers on the geometric characteristics of the produced fabrics was investigated. For this purpose, yarn-yarn distances and density, yarn lengths and yarn angles were measured. The effect of the number of layers on the geometric parameters was limited. Yarn-to-yarn distances in plain-weave fabrics were found to be greater when compared to other types of fabrics whereas the yarn density decreased in plain woven fabrics due to a large number of interlacements. This shows that in composite form, the fiber volume fraction in the filling and z-directions will be lower in the semi-interlaced fabrics when compared to the non-interlaced orthogonal structures. It was also shown that filling and warp angles are a function of weave type while z yarn angle is associated with the weaving operations such as beat-up, multi-layer filling insertion and warp yarn let off.