The aim of the present study was to detect entheseal abnormalities by means of ultrasonography (US) in patients with psoriasis. We evaluated 24 patients with psoriasis who underwent clinical and ultrasonographic examination of both lower limbs at the calcaneal insertions of the Achilles tendons and at the flexor and extensor tendons of all fingers of the hand. Fourteen patients with psoriatic arthritis were used as controls. US was performed using a real-time scanner (ATL SDI 3000) with a 5-12 MHz linear array transducer. Longitudinal and transverse scans of the talocrural joints, Achilles tendons and both the flexor and extensor tendons of the fingers of both hands were obtained at rest and during active and passive movements. On clinical examination no entheseal site was abnormal, but on US examination 33% of patients showed abnormalities. In particular, six psoriasis patients (25%) who were asymptomatic showed effusion around the extensor tendon of the first digit of the left hand and around the extensor tendon of the third and fourth digits of both hands; two patients (8.3%) showed a hypoechoic nodular formation of the flexor tendon sheath of the left hand. We conclude that entheseal abnormalities not detected at clinical examination were present in 33% of patients with psoriasis who underwent US examination. Therefore, we suggest the routine use of ultrasonography in the early diagnosis and in treatment and follow-up of patients with tendon enthesopathy, since these factors may have implications for therapy.