Bone mass is determined throughout life by modeling and remodeling mechanisms. Trabecular bone consists of a network of trabeculae (plates and rods) whose distribution is highly anisotropic: trabeculae are disposed parallel to the resultant of stress lines (Wolff's law). The trabecular microarchitecture appears to be conditioned by mechanical stresses exerted on skeletal bones. Few clinically validated methods are available to assess and monitor the bone microarchitecture in bone diseases. The best-developed is bone histomorphometry, with the use of new algorithms to appreciate various 2D characteristics of the trabeculae, such as thickness and connectivity. Several studies have shown that several independent techniques should be used to study microarchitecture parameters. X-ray microtomography (micro CT), microMRI and synchrotron devices can give non destructive 3D measurements of the trabecular microarchitecture of bone specimens. This review describes advances in our knowledge of bone microarchitecture, its role in bone diseases such as osteoporosis, and methods of 2D and 3D histological evaluation.