Aim: The aim of this study is to determine the vitamin D level in patients with RA (Rheumatoid Arthritis) and association with clinic and laboratory parameters and quality of life. Material and Method: Out of 111 patients with RA and 107 healthy controls who were admitted to Ahi Evran University Training and Research Hospital were included in this study. Patients underwent clinical, laboratory, functional, and quality of life examination. Laboratory tests used for patient evaluations included complete blood count, erythrocyte sedimentation rate (ESR), C-reactive protein level (CRP). Disease activity was calculated by DAS28 (Disease Activity Score) and functional and quality of life was examined by RAQoL (Rheumatoid Arthritis Quality of Life), HAQ (Health Assessment Questionnaire). Larsen score was calculated to assess the radiographic damage. Results: There was no significant difference between the patient and control groups regarding age, sex and vitamin D level (p > 0.05). There were no correlation between vitamin D and Larsen score, RAQoL, HAQ, ESR, and CRP (p > 0,05). We found negative correlation between DAS28 (Disease Activity Score) and vitamin D (r = -0,416, p = 0,014). We found negative correlation between morning stiffness and vitamin D (r = -0,454, p = 0,007). Patients with RA were divided into two groups with D vitamin deficiency (0-19 ng / mL) and vitamin D ( > 20 ng / mL). There was a negative correlation with morning stiffness in the group with vitamin D deficiency (r = -0,454, p = 0,007). There was a negative correlation between DAS28 score and vitamin D deficiency (r = -0.416, p = 0.014). Discussion: This study presents a negative correlation between serum vitamin D level and DAS28. Since vitamin D has autoimmune roles, deficiency or inadequacy can cause flaring in patients with RA. In the light of these findings, we recommend vitamin D supplementation.