The undercarboxylated osteocalcin (ucOC) level is increased in the elderly and postmenopausal women compared with the young, healthy, and reproductive women. The high level of serum UcOC reflects the vitamin K2 deficiency which not only results in high skeletal turnover, low bone quality, and low bone density, but also increases a risk of fracture. The objective of the study is to measure the ucOC level, the 25-hydroxy vitamin D (25(OH)D) levels, and the prevalence of vitamin K2 and vitamin D deficiency in Thai female patients with hip fracture. The serum UcOC and 25(OH)D levels of the 40 female patients with hip fracture (the mean age 77.2 +/- 9.7 years) were measured and compared to the control group of the 47 randomly selected female volunteers (the mean age 75.2 +/- 8.1 years) without osteoporosis-related problems. The serum level of UcOC (median) in the female patients with hip fracture was significantly higher than the control group (p = 0.0001). Fifty-three percent had the serum UcOC level above the cut-off point at 2.314 ng/ml and 83% had lower serum 25(OH)D than the cut-off point at 30 ng/ml. The serum UcOC levels; however, were not correlated with 25(OH)D levels (r = 0.191, p = 0.237). The high prevalence of vitamin K2 and vitamin D deficiency was found in the Thai female patients with hip fracture. The additional treatment with vitamin K2 supplement besides calcium and vitamin D is a beneficial effect for osteoporosis.