OBJECTIVES: Fatigue is an aspect of psoriatic arthritis (PsA), which is important to patients. The objective was to evaluate magnitude of fatigue in PsA patients and to assess factors that might explain high levels of fatigue. METHODS: This was an ancillary analysis of a cross-sectional study in 13 countries of unselected PsA patients who fulfilled the CASPAR criteria. Patient-perceived importance of fatigue was assessed through a priority exercise. Levels of fatigue were assessed by a numeric rating scale (range 0-10). Factors potentially associated with fatigue>5/10: i.e., demographic variables (age, gender, disease duration, education level) and disease related characteristics including joint counts, C-reactive protein, skin psoriasis, axial involvement, enthesitis, dactylitis, structural damage, were assessed by univariate, multivariate logistic and multiple linear regression. RESULTS: In all, 246 patients were analysed: mean±standard deviation age 51.2±13.0years, mean disease duration 9.9±10.1years, mean DAS28 3.5±1.3. Fatigue was ranked second in patient-perceived importance, after pain. Magnitude of fatigue was high: mean fatigue 5.0±3.0. Fatigue>5/10 was well explained (variance explained 73%) by skin psoriasis (odds ratio 4.67 [95% confidence interval 1.05; 20.72]), tender joints (1.30 [1.01; 1.68]) and lower education level (1.09 [1.02; 1.23]). In the multiple linear regression model, fatigue was explained by skin psoriasis, tender joints, enthesitis, female gender, education level. CONCLUSIONS: Fatigue is a priority for PsA patients. Fatigue levels were high in these patients and fatigue>5/10 was mainly associated with disease-related factors but also patient-related variables, indicating that the etiology of fatigue in PsA is multifactorial.