Three cases of hypothenar hammer syndrome are reported in manual workers who experienced repeated traumatism of the palm of the hand either because of personal habit or the use of professional tools. Hemodynamic examination of the upper limb was performed by plethysmography (Perivein Etna) and Doppler ultrasound (8 MHz) complemented by angiography by direct puncture of the humeral artery. Ultrasonography was performed using a 7.5 MHz probe (Sononranger) for exploration of the ulnar artery at the wrist and in its course through the palm. The 3 patients presented aneurysmal dilatation of the ulnar artery in the palm, complicated by postembolic thrombosis of the collateral arteries of the fingers. The ulnar artery lesion was permeable 1 time, already thrombosed 1 time and thrombosed secondarily 1 time. Ultrasonography of the palm showed suspected aneurysm of the ulnar artery in 2 patients: one case was confirmed by angiography, whereas the other remained only suspect since the thrombosed ulnar artery was not opacified. The third patient presented an ulnar artery thrombosis without true aneurysmal dilatation. It may be concluded that ultrasonography can show suspected aneurysmal dilatation of the ulnar artery and be complementary to arteriography when the ulnar artery is thrombosed.