Vitamin D deficiency is a common health problem worldwide and tends to be a risk factor for all-cause mortality. We evaluated the effect of continuous low-dose oral daily and loading dose of oral weekly and loading monthly intramuscular (IM) vitamin D3 regimens on circulating levels of total 25(OH)D and in vitamin D deficient females, and between non-obese and obese subgroups. A total of 231 vitamin D deficient females were included to the study. According to treatment regimen, patients were divided into three groups: daily continuous oral, loading dose of weekly oral and monthly intramuscular. All patients in treatment groups were divided into non-obese (105) and obese (126) groups. Serum 25(OH)D and parathormone (PTH) levels were evaluated at baseline and at the third and sixth month. In obese patients oral weekly loading regimen and in non-obese patients oral daily continuous regimens were found to be more potent. Baseline PTH levels decreased when compared with the third and sixth months (p < 0.001), but between the third and sixth months it was not changed (p = 0.783). Oral daily regimen in non-obese patients and loading weekly oral regimen in obese patients were more effective in achieving the target levels of 25(OH)D concentration above 30 ng/ml and provided a stable plasma vitamin D concentration over a long period of time.