The aim of this study was to identify potential markers of aggressive joint manifestations and HLA associations in patients with psoriatic arthritis (PsA) in northern Sweden. Patients with PsA were examined clinically, with laboratory tests and radiologically. The classification of the disease was based on peripheral and/or axial engagement. HLA B17, B37 and B62 were significantly increased in PsA patients. Univariate analyses suggest that the HLA antigens B37, B62 and some clinical variables were associated with disease course. However, in multivariate analyses distal interphalangeal joint affliction and polyarticular manifestations were the only variables remaining significantly associated with irreversible joint destruction or deformity. There were no significant effects of HLA antigens. In this cross-sectional study, clinical manifestations were more reliable predictors of aggressive joint damage than were specific HLA antigens. However, HLA antigens seemed to modify the expression of the joint disease rather than being involved in joint disease susceptibility.