Aim: Nail involvement is common in psoriatic arthritis. This study assesses clinical characteristics, nail psoriasis prevalence, and impact of nail psoriasis on disease activity in patients with psoriatic arthritis (PsA). Method: This cross-sectional multicenter study was conducted by the Turkish League Against Rheumatism using PsA patients recruited from 25 centers. Demographic and clinical characteristics of PsA patients, such as disease activity measures, quality of life, and nail involvement findings were assessed during routine follow-up examinations. Patients were divided into two groups according to the presence or absence of nail psoriasis and compared using the χ2 test or Fisher exact test for categorical variables and the t-test o...