Psoriasis is a T-helper-1 (Th1)/Th17-mediated chronic inflammatory skin disease, characterised by hyperproliferation of keratinocytes. Psoriasis and cardiovascular disease share similar pathogenic mechanisms such as vascular endothelial cell dysfunction, oxidative stress and metabolic syndrome. 25-hydroxy vitamin D is an immune-regulatory hormone, with the ability to reduce cellular proliferation in psoriasis. Ischaemia-modified albumin (IMA) is a marker of oxidative stress. This study examined 25-hydroxy vitamin D, IMA and high-sensitivity C-reactive protein (hs-CRP) levels in patients with psoriasis, in comparison with healthy controls and their possible association with disease severity. A total of 43 cases of psoriasis and 43 controls were included in this cross-sectional study, and severity grading was performed according to psoriasis area severity index (PASI) scoring. Serum 25-hydroxy vitamin D, IMA and hs-CRP were evaluated in all study subjects. In psoriasis, 25-hydroxy vitamin D showed a significant decline, while hs-CRP and IMA levels were significantly elevated, as compared with controls. Serum 25-hydroxy vitamin D showed a significant negative correlation with PASI score. hs-CRP and IMA showed a significant positive correlation with PASI score. Significant negative correlation was observed between 25-hydroxy vitamin D and hs-CRP; 25-hydroxy vitamin D and IMA levels in psoriasis. The results indicate that psoriasis is associated with significantly lowered 25-hydroxy vitamin D levels, along with increased systemic inflammation and oxidative stress, especially in severe disease. Thus, vitamin D supplementation might reduce systemic inflammation and oxidative stress and help in delaying the pathogenesis of co-morbidities associated with psoriasis.