Objective To investigate the clinical and radiological features of psoriatic arthritis,and to offer a basis to the formulation of diagnostic and classification criteria for psoriatic arthritis with high sensitivity and specificity.Methods A cross-sectionaI and retrospective study was performed to analyze the clinical and radiological features of 61 patients with confirmed diagnosis of psoriatic arthritis,along with the clinical onset features and evolution rules of the disease.These features were compared with the traditional criteria for psoriatic arthritis.Results These patients exhibited divelse clinical and radiological features.Of the five types of arthritis involved in the traditional criteria,distal interphalangeal arthritis was diagnosed in 38 patients,asymmetric pauciarthritis in 5 padents,symmetric polyarthritis in 33 patients,arthritis mutilans in 4 patients,ankylosing spondylitis in 12 patients,and they symptomatically overlapped each other.Other types of arthropathy,which were not included in the traditional criteria,were also observed in these patients.For example,undifferentiated spondyloarthropathy was diagnosed in 17(28%)patients,peripheral enthesitis in 19(31%)patients,and arthritis in privileged sites in 6(10%)patients(5 in temporomandibular joint and 1 in sternoclavicular joint).In the case of radiological profiles in the traditional criteria,pen cap-like abnormality due to bone absorption was noticed in 6 cases,sharpening of finger tips in 6 cases,bamboo-like syndesmophyte in 5 cases,sacroiliitis grade 3-4 in 8 cases.Other radiological manifestations which were beyond the traditional criteria but found in the patients included fluffy periostitis(n=19),hyperostosis with ill-defined edge(n=12),bone erosion(n=25),local and assymmetry syndesmophyte(n=8),sacroiliitis grade 2-3(n=8),etc.The clinical findings hinted that psoriatic arthritis had diverse onset features,and took on a progressive course.Conclusions Psoriatic arthritis displays a diverse clinical,radiological and onset feature as well as a complicated evolution.The traditional criteria only cover partial characters,and could not satisfy the need for early diagnosis and accurate classification of psoriatic arthritis,and there is an urgent demand for the formulation of a new diagnostic and classification criteria for this disease.