Psoriasis is considered an independent risk factor for cardiovascular diseases (CVD). It is crucial to find new biomarkers that help with the early detection of endothelial dysfunction. This study aimed at investigating the clinical relevance of serum endocan concentrations in psoriatic patients and their value in the detection of endothelial dysfunction (ED). This is an observational study that was conducted on 60 patients with psoriasis and an equal number of healthy individuals as a control group. For the identification of patients with ED, flow-mediated vasodilatation (FMD) was assessed. The levels of endocan in psoriatic patients (versus levels in normal individuals) and the relation between endocan levels and the indicator of endothelial dysfunction (FMD%) were assessed. This study showed a significantly higher prevalence of ED in psoriatic patients, comprising 71.1% of the patients versus 35% in control subjects. Serum concentrations of endocan were significantly higher among psoriatic patients in comparison with healthy individuals. Higher serum endocan concentrations were detected in patients with ED. Correlation analysis showed that serum endocan concentrations were positively correlated with Psoriasis Area and Severity Index (PASI) score, and C-reactive protein (CRP), but there was significant negative correlation with FMD%. In conclusion, patients with psoriasis are particularly predisposed to endothelial dysfunction as an earlier form of CVD. Endocan showed significant associations with psoriasis-associated ED. We suggest its use in the routine screening of patients with psoriasis.