Background: Intestinal symptoms are common in patients with hidradenitis suppurativa (HS). HS patients may experience a broad spectrum of chronic inflammatory intestinal disorders (CIID), not exclusive to inflammatory bowel diseases, which are diagnosed by colonoscopy and intestinal biopsies. The frequency of CIID in patients with HS has not been investigated. Objective: The objectives of this study were to determine the occurrence of CIID in HS and characterise this clinical population. Furthermore, the feasibility of using fecal calprotectin (FC) test or anti-Saccharomyces cerevisiae antibody (ASCA) levels to assess the colonic inflammation of CIID in HS patients was investigated. Methods: All newly diagnosed and untreated HS patients (n=74) were referred to a gastroenterologist for FC followed by colonoscopy after informed consent. C-reactive protein (CRP), white blood cell count, nucleotide-binding-oligomerisation-domain-containing-protein-2 (NOD2) polymorphism, and ASCA levels were measured. Patients were divided into HS-only and HS with CIID (HS+CIID) groups, based on the absence or presence of CIID. Laboratory and clinical parameters (age, gender, HS onset, clinical stage, family history, body mass index (BMI), smoking) were compared between the groups. Results: Thirteen patients complained gastrointestinal symptoms prior to any examination, including 11 in the HS+CIID group. The CIID frequency in HS was 28.4% (n=21/74), based on colonoscopy and histology. Significantly more patients had severe disease state in the HS+CIID group compared with the HS-only group, and BMI was significantly lower in the HS+CIID group (28.20±5.58 vs. 32.74±6.45, p=0.006). FC positivity occurred significantly more in HS+CIID patients compared with HS-only patients (90.48% vs. 3.77%, p<0.001), and ASCA IgG levels were significantly elevated in HS+CIID patients (22.08±23.07 vs 8.41±10.94 U/mL, p=0.001). The FC test identified HS+CIID patients with 96.23% specificity and 91.3% sensitivity, while ASCA displayed 77.8% sensitivity and 76.3% specificity. Blood count, CRP and the presence of NOD2 polymorphisms were indifferent between the two groups. Conclusion: A high frequency of CIID was detected in the examined HS population. The non-invasive FC test has high sensitivity and specificity for diagnosing CIID in HS patients. Concomitant CIID and HS may indicate the need for an early-start for biological treatment.