This research focuses on the fabrication of glass fiber/epoxy organoclay nanocomposites as well as on the investigation of organoclay effect on transverse tensile strength and in-plane shear strength of the nanocomposites. To demonstrate the organoclay effect, three different loadings of organoclay were dispersed respectively in the epoxy resin using a mechanical mixer followed by sonication. The corresponding glass/epoxy nanocomposites were produced by impregnating dry glass fiber with organoclay epoxy compound via a vacuum hand lay-up procedure. For evaluating transverse tensile strengths, the unidirectional coupon specimens were prepared and tested in the transverse direction. Results indicate that with the increment of organoclay loadings, the glass/epoxy nanocomposites demonstrate higher transverse tensile strength. On the other hand, the in-plane shear strengths were measured from [± 45]s laminates. It is revealed that when the organoclay loadings increase, the in-plane shear strength of glass/epoxy nanocomposites also increases appropriately. Scanning Electron Microscopy (SEM) observations on the failure surfaces indicate that the increasing characteristics in transverse and in-plane failure stresses may be ascribed to the enhanced fiber/matrix bonding modified by the organoclay.