Background: Adenosine deaminase (ADA) is an enzyme involved in purine metabolism and it is a marker of nonspecific T-cell activation. Few studies have shown high levels of ADA in the epidermis and sera of psoriatic patients. Other inflammatory markers such as high-sensitive C-reactive protein (hsCRP), erythrocyte sedimentation rate (ESR), and serum uric acid (SUA) have shown correlations with psoriasis area severity index (PASI) score. The correlation between ADA and PASI score is still a matter of debate. Aims: The aim of this study was to evaluate serum ADA, hsCRP, SUA, and ESR in psoriatic patients and their correlation with PASI score. Patients and Methods: This study included 60 psoriatic patients divided according to PASI score into three groups (mild, moderate, and severe) each containing 20 patients. PASI score <10 was defined as mild, (10–20) moderate, and >20 severe. Twenty healthy subjects of matched age and sex were included as control. Serum ADA, hsCRP, SUA, and ESR were evaluated for patients and controls. Correlations of ADA, hsCRP, SUA, and ESR with PASI scores were done. Results: While ADA, hsCRP, SUA, and ESR showed a significant increase in psoriatic patients compared with that of the controls (P<001), they showed no significant difference between different psoriatic groups (P>0.05) and no correlations with PASI score (P>0.05). The frequency of joint affection increased with increasing severity of psoriasis (5%, 10%, and 25% in mild, moderate, and severe psoriasis, respectively). Conclusion: Serum ADA, hsCRP, SUA, and ESR showed higher levels among psoriatic patients than in controls. The increased ADA in psoriatic patients supports the role of T-cell activation and proliferative disorder in the pathogenesis of psoriasis. No significant correlations were found between these biomarkers and PASI score. Further studies are needed to validate these biomarkers as diagnostic and prognostic factors in psoriasis.