OBJECTIVE Because of doubts in early clinical assessment and full documentation of all various cases of psoriatic arthritis outside of rheumatologic centres a clinical study in a dermatologic department of a rehabilitation clinic was performed. METHODS 148 patients between 1996 and 1999 were interviewed and examined clinically. 27 (18.2%) of them had osseous joint processes proved by X-ray (severe cases). 90 (60.8%) patients had no radiologic changes but a positive history of joint pain (mild cases). 31 (21%) patients had none of the problems (Control group). Blood specimens were taken in order to reveal inflammations (ESR, CRP, RF, ASL, uric acid, and leucocytes). Exclusion criteria were other arthritides, multiple osteoarthritis and consolidated fractures of joints. The groups were compared together. RESULTS Whereas palpable joint crepitations did not turn out as a reliable specific sign, pressure pain on acromioclavicular joints and MTP joints, impingement signs of the shoulders, deformities of toes and flexor tendon swellings of the hand were usable tools in diagnosing a severe psoriatic arthritis in this study. The ESR, ASL, CRP, and uric acid were elevated significantly more often in severe than in mild cases. Moreover, the time period between the first onset of skin lesions and joint pain was shorter in severe cases than in mild cases (9.86 vs 13.8 years). CONCLUSIONS The diagnostic relevance of criteria, for example of the well-known European Spondylarthropathy Group (ESSG), may be improved by new early screening criteria.