The objective: to assess the level of vitamin D and its relationship with carbohydrate metabolism in women with metabolic syndrome in the I trimester of pregnancy. Materials and methods. 120 pregnant women were examined, of which 60 patients were diagnosed with metabolic syndrome before pregnancy (main group) and 60 patients without this pathology (control group). All women were measured for fasting blood glucose, glycated hemoglobin, immunoreactive insulin, HOMA-IR index, and serum vitamin D levels. Results. In women in the main group, the average level of vitamin D was 15.76±3.77 ng/ml, in the control group – 17.20±3.76 ng/ml. The concentration of vitamin D less than 20 ng/ml in the main group was found in 70.0% of patients, in the control group – in 51.7%, 20–30 ng/ml – in 30.0% and 48.3%, respectively (p<0.05). The mean body mass index was significantly higher in women of the main group relative to the control group (p=0.041) and in patients with metabolic syndrome did not differ from the values in women with vitamin D deficiency and insufficiency. However, body mass index was significantly higher in the presence of vitamin D deficiency between patients with and without metabolic syndrome (p=0.001). There was a significant difference in the concentration of immunoreactive insulin and the value of the HOMA-IR index between pregnant women with vitamin D deficiency and metabolic syndrome (p=0.040) and without it (p=0.023). Serum 25(OH)D levels in early pregnancy in persons with metabolic syndrome positively correlated with glucose (r=0.361; p>0.05), HbA1c (r=0.355; p>0.05) and HOMA-IR (r=0.239; p>0.05) in vitamin D deficiency and negative in 25(OH)D insufficiency: r=-0.795 (p<0.05), r=-0.464 (p>0.05) and r=-0.500 (p>0.05), respectively.Conclusions. Pregnant women with metabolic syndrome and vitamin D deficiency, compared with pregnant women without this syndrome, may have higher levels of immunoreactive insulin and HOMA-IR index. Between the women with the deficiency and insufficiency of vitamin D and the parameters of carbohydrate metabolism in the metabolic syndrome a multidirectional correlation was revealed.