BACKGROUND:Recently epidemiological studies showed that low vitamin D is linked to airway hyperresponsiveness, decreased lung function, poor asthma control, and steroid–resistant asthma.AIM:We investigated the relationship between Vitamin D, inflammation with circulating IL-33 and lung function in 30 patients with severe uncontrolled asthma.MATERIALS AND METHODS:The study included 30 patients with severe uncontrolled asthma. In each of them were measured serum levels of IL-33 and Vitamin D by the ELISA method. The pulmonary function is measured by basic spirometry parameters, FEV1. The results were statistically elaborated according to the Pearson’s Correlation Tests.RESULTS:The results showed statistically insignificant correlation between Vitamin D and IL-33, and Vitamin D with FEV1 (Vit.D/IL-33; r = 0.11323, p = 0.551); (Vit.D/FEV1; r = -0.1005; p = 0.597) Correlation between IL-33 and FEV1 is negative but statistically significant (IL-33/FEV1; r = -0.5248; p = 0.003).CONCLUSION:Because there are little studies about the link between vitamin D and asthma, further research to clarify the mechanism how vitamin D control the activity of CD4+ T cells and the related Th2-type cytokines in the parthenogenesis of asthma.