We studied the ultrasonographic (US) features of the pes anserinus insersion (PA) and subcutaneous medial knee fat in patients clinically diagnosed of pes anserinus tendino-bursitis (PATB) syndrome. Thirty seven consecutive patients with suspected PATB were clinically evaluated and their knees examined using a 7.5 MHz linear probe. In twenty-three patients with unilateral clinical PATB (group A) the painful knee was compared with their painless opposite knee. Six patients with bilateral clinical PATB (group B) were compared with 6 healthy controls (group C). All patients were women with radiographic knee osteoarthritis in 93% and body mass index > 27 in 75%. US pes anserinus tendinitis was found in one symptomatic knee and pes anserinus bursitis in two symptomatic knees and in one asymptomatic knee. No US signs of panniculitis were found in patients and controls. In conclusion, patients diagnosed of PATB syndrome in rheumatology rarely have US tendinitis or bursitis of the PA.