BACKGROUND The role ofparathyroid glands (PTG) ultrasonography (US) in hemodialysis patients with secondary hyperparathyroidism (SHPT) is still controversial. The present study aimed at evaluating the relationship between US findings and SHPT degree as well as therapeutic outcome. METHODS Twenty hemodialysis patients with moderate SHPT and 15 with severe SHPT underwent US to assess the PTG number, maximum longitudinal diameter (MLD), structural (1-hypoechoic, 2-slight heterogeneous, 3-high heterogeneous, 4-nodular) and vascular patterns (1-slight, 2-medium and 3-high). RESULTS PTG number, MLD and US patterns were correlated with iPTH levels. MLD of patients with moderate or severe SHPT was 7.2 +/- 2.3 and 15 +/- 5.1 mm (p < 0.001). Most patients with moderate SHPT showed a single PTG with an MLD <9 mm associated with 1-2 structural and vascular pattern, whereas patients with severe SHPT exhibited more than one PTG with MLD >9 mm and 3-4 structural and vascular patterns. Thirteen patients were responders to treatment and 22 nonresponders. In nonresponders, a higher number of PTG was observed as well as higher echostructural and vascular patterns. In 14 patients who underwent parathyroidectomy, no differences were found between PTG US MLD and pathology diameter. All PTG with evidence of 3-4 structural and vascular score at ultrasound showed nodular hyperplasia at pathological examination. CONCLUSIONS The adopted classification of US findings is correlated with SHPT degree and therapeutic outcome and might be an adjunctive predictive method useful to assess the SHPT severity and to plan the therapeutic strategy.