Background: Endocan is a specific molecule of human endothelial cell. It was accepted as a marker of endothelial dysfunction that is widely involved in psoriasis development. Our aim was to evaluate the relation between serum endocan levels and severity of psoriasis vulgaris. Methods: Twenty-two patients with psoriasis vulgaris were involved. We measured serum endocan, c-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Psoriasis severity was evaluated by Psoriasis Area and Severity Index (PASI) score. Results: The mean serum level of endocan was 154±49.3 pg/ml with a range from 59 to 210 pg/ml. Its level was statistically significant increase in moderate and severe psoriatic patients compared to mild psoriatic patients. No statistically significant correlations were detected between serum endocan and CRP (P=0.11) and ESR(P=0.16). In contrast, a very highly statistically significant positive correlation was detected between endocan and disease severity(p=0.001). Conclusions: Serum endocan can be a promising marker that correlates with psoriasis vulgaris severity.