Hypovitaminosis D in the elderly causes falls and fractures as a result of impaired neuromuscular functions and also may be a reason for nonspecific musculosceletal pain. The aim of this study is to investigate the benefits of a single dose per os or parenterally administrated vitamin D on increasing the quality of life and functional mobility and decreasing the pain in the elderly. The community-dwelling elderly subjects over 65 years age were included in the study. The subjects were given 300.000 IU Vitamin D via per os and parenteral route and assessed after 4 weeks. The serum creatinine, calcium, phosphorous, ALT, ALP, 24-h urine calcium excretion, PTH, and vitamin D levels, as well as VAS (visual analog scale) for pain assessment, functional mobility with TUG (timed up and go test) and quality of life with SF-36 before and after the treatment were evaluated. The serum vitamin D levels were measured by the RIA method. The subjects were divided into four groups each consisting of 30 subjects. The 1st group took i.m. vitamin D, the 2nd group took i.m. placebo, the 3rd group took p.o. vitamin D, and the 4th group took p.o. placebo. The mean age of all the participants was 70.1 ± 4.3 years. There was no difference in the age and gender between the groups (P > 0.05). After treatment, the PTH level of first group was decreased (P = 0.0001) and the vitamin D level increased (P = 0.0001) significantly. In the third group, the PTH level of first group was decreased (P = 0.0001) and the vitamin D level increased (P = 0.004) and the 24-h calcium excretion in urine (P = 0.015) increased significantly. When the pain, the functional mobility, and the quality of life were evaluated, in the first group, the TUG (P = 0.0001) and the VAS (P = 0.0001) decreased significantly, whereas the SF-36 subtitles: physical functioning (P = 0.0001), role physical (0.006), bodily pain (P = 0.0001), general health (P = 0.007), social functioning (P = 0.05), and mental health (P = 0.048) increased significantly. In group two, the VAS (P = 0.001) decreased, the role physical (P = 0.009), and role emotional (P = 0.034) increased significantly; In group three, the TUG (P = 0.0001) and the VAS (P = 0.002) decreased, whereas the physical function (P = 0.0001) and role physical (0.001) increased significantly; In group four, the VAS (P = 0.007) decreased significantly. The megadose vitamin D administration increases quality of life, decreases pain, and improves functional mobility via po or im route in the elderly.