Psoriasis is a common immune-mediated inflammatory condition that primarily affects skin and nails. 6-41% of psoriasis patients develop psoriatic arthritis (PsA). The ways in which PsA can manifest itself include peripheral arthritis, axial spondyloarthritis, dactylitis and enthesitis. This heterogeneous clinical picture makes it sometimes difficult to recognise PsA,potentially resulting in permanent joint damage and functional impairments. Some people see psoriasis and PsA as 2 manifestations of a single disease because the multifactorial origins of psoriasis and PsA are largely overlapping. Psoriatic conditions are associated with a high burden of disease, reduced quality of life and comorbidities, including psychiatric and cardiovascular conditions. In recent years, several immunological pathways, immune cells and cytokines have been identified as important factors in pathophysiology and as new therapeutic targets. For many PsA patients treatment with disease modifying anti-rheumatic drugs leads to significant improvement of symptoms and quality of life.