Abstract： Objective In order to confirm the value of high resolution frequency (HFUS) ultrasonography in the early diagnosis of psoriatic arthritis (PsA).Methods Twenty-nine patients with psoriatic arthritis reporting sixty-nine finger pain and 30 patients with rheumatoid arthritis reporting seventy finger pain and 20 healthy volunteers underwent X-ray and US evaluation.The ultrasonographic characteristics and blood flows in the joints were checked with high resolution ultrasonography.Bilateral joints were compared each other in every patient.Comparisons between groups were tested by x2 test.Results Sonographic positive signs were found in all the involved joints in 29 PsA patients,joint effusion in 42 fingers (61％).Synovial thickening was found in 38 fingers (55％).Bone erosions were found in 28 fingers (41％),tenosynovitis were found in 40 fingers (58％),soft tissue inflammation was revealed in 29 fingers (42％).Enthesitis were found in 30 fingers (43％).In RA patients,joint effusion was found in 52 fingers (74％) and synovial thickening in 48 fingers (69％).Bone erosions were found in 33 fingers (47％).Tenosynovitis,soft tissue inflammation and enthesitis were not found in RA patients.Conclusion High resolution ultrasonography is an easy,safe and effective method for the early diagnosis of pathological changes of small joints in psoriatic arthritis.