Objectives: The objective of this study is to assess the relationship between coeliac disease antibodies, vitamin D serum concentration and psoriasis. The additional objective is to test the relationship between vitamin D serum concentration and bone mineral density in patients with psoriasis and psoriatic arthritis. Study Design: Case - control study. Participants and Methods: The study included 112 participants, 60 with psoriasis in experimental group, and 52 healthy subjects in control group. The experimental group was subdivided in subgroup of patients with psoriasis and psoriatic arthritis (N=17), and subgroup of patients with psoriasis only (N=43). After informed consents were obtained, DLQI (Dermatology Life Quality Indeks) score, PASI (Psoriasis Area and Severity Indeks) score and vitamin D questionnaire were administered. Laboratory tests included assessment of vitamin D serum concentration, anti-deaminated gliadin peptide antibodies, anti-gliadin antibodies, anti-tissue transglutaminase antibodies, ESR (erythrocyte sedimentation rate), CRP (C-reactive protein), ALP (Alkaline Phosphatase level test), calcium, PTH (parathyroid hormone) and phosphate level. Bone mineral density was assessed by DXA (Dual X-ray Absorptiometry) scan in two regions of interest: lumbar spine and left femoral neck. Results: In patients with psoriasis, positive anti-gliadin antibodies of IgG (Immunoglobulin G) and IgA (Immunoglobulin A) class were found more frequently and in higher serum concentrations than in healthy controls. The same was established for anti-tissue transglutaminase antibodies of IgG class as well as anti-deaminated gliadin peptide antibodies of IgA class. Median level of vitamin D serum concentrations in all subjects was 19,6 ng/mL (interquartile range11,3 - 23,7 ng/mL ), that represents vitamin D deficiency. No difference in vitamin D serum concentration was observed between patients with psoriasis and healthy subjects. Bone mineral density is at osteoporosis level in 10 % of patients with psoriasis when measured in lumbar spine, and in 1,7 % of the patients when measured at femoral neck. Patients with psoriatic arthritis and psoriasis have lower mineral bone density measured at lumbar spine when compared to patients with psoriasis only. Patients with psoriatic arthritis showed a statistically longer average duration of psoriatic disease. Conclusion: No relationship exists between vitamin D serum concentration and psoriasis. There is relationship between positivity to coeliac disease antibodies and psoriasis, anti-gliadin antibodies in particular. Osteoporosis does not represent a significant comorbidity for patients with psoriasis and psoriatic arthritis.