Bone quality is thought to encompass the structural and material properties of bone. Bone collagen crosslinking plays important roles in bone strength. The quantitative and qualitative deterioration of lysyl oxidase control and non enzymatic cross-links (advanced glycation end products, AGEs, pentosidine) of collagen in patients with osteoporotic femoral neck fracture and diabetes, and chronic kidney disease might be affected by increased oxidative stress and glycation. A higher urinary or plasma pentosidine and homocysteine levels were an independent risk factor for osteoporotic fracture. If confirmed in large, prospective trials, measurements of serum homocysteine and serum or urine levels of pentosidine might be characterized as markers reflecting bone collagen deterioration.