Background: Psoriasis represents an example of an autoimmune disease where adaptive immune system activation, T helper 17 secretory cytokines secretion such as IL 17 and IL 21, and self–antigen intolerance are the hallmarks of its pathology. Hidradenitis suppurativa on the contrary, could be described as a neutrophilic dermatosis disease while recurrent abscess formation and skin fibrosis compose the clinical features. Inflammatory bowel diseases association with diverse dermatological diseases is well known. Objectives: To evaluate the role of the diagnostic application of fecal calprotectin (FCP) in patients with either hidradenitis suppurativa or psoriasis. Patients and Methods: A cross-sectional study was done on 20 patients with varying severity of plaque psoriasis and 10 patients with hidradenitis suppurativa (HS). Demographic data, duration of illness, area extent affected, gastrointestinal symptoms, and severity scores were taken such as Psoriasis Assessment and Severity Index (PASI) score and Hurley staging for psoriasis and HS retrospectively. A fecal calprotectin (FCP) assay was also tested. Results: While the psoriasis group demonstrated significantly higher age (median = 51 vs. 25 years, P < 0.001) than the HS group, hidradenitis suppurativa showed significantly higher FCP levels (median = 215 vs. 83, respectively, P = 0.013). Significant strong positive correlations between FCP and severity were observed in the hidradenitis suppurativa group (r = 0.921, P < 0.001). Conclusion: To our knowledge, our study could be the first comparative study between hidradenitis suppurativa and psoriasis in relation to fecal calprotectin.