Background:Vitamin D is linked to musculoskeletal function in our bodies, and its deficiency is a common health problem all over the world. Low back pain (LBP) is an important health problem in terms of low quality of life, loss of work power, and cost of diagnosis and treatment approaches.Aim and objectives: The purpose of this study is to investigate the relationship between pain severity and vitamin D deficiency in female patients who came in with OPD with LBP. Materials and Methods:The present was a retrospective, observational study.The female patients aged between 18 and 70 who came to OPD of orthopaedics and gynaecology between January 2019 and June 2019 were examined retrospectively. Serum 25-hydroxyvitamin D (25(OH)D) level, Visual Analogue Scale (VAS), age, education level, marital status, working status, and body mass index (BMI) values recorded in patient files were included in the study. The limit value of vitamin D was accepted as 20 ng/mL. Patients were divided into two groups according to their levels of vitamin D. Patients with serum 25(OH)D levels below 20 ng/mL were considered to have a deficiency of vitamin D (Group 1), and patients with 20 ng/mL and over 20 ng/mL values were considered normal in terms of vitamin D (Group 2).Results:The level of vitamin D was measured in 98 patients aged 18–70 who applied to our hospital's due to LBP during the study period. The deficiency of vitamin A was detected in 84 (85.7%) of the patients, while vitamin D was found in 14 (14.3%) as normal. Groups were similar in terms of age, gender, BMI, educational level, marital status, and working status (p > 0.05); however, there was a statistically significant difference between the two groups in terms of VAS score and levels of Vitamin D (P < 0.001 and P < 0.001, respectively). While there was a negative correlation between D vitamin level and VAS score (r = 0.594, P < 0.001), there was no correlation between age, gender, BMI, education level, marital status, and working status (P > 0.05).Conclusions:The deficiency of Vitamin D is often asymptomatic, and it can also cause bone and muscle pain. In our study, we determined that the severity of pain increased in female patients with LBP as the deficiency of Vitamin D increased. For this reason, we recommend evaluating the level of vitamin D in patients with LBP.