Hepatic artery pseudo-aneurysm is a rare but severe complication of liver transplantation, which generally requires immediate surgical or angiographic treatment. The diagnosis is usually made by splanchnic percutaneous angiography. We report a case of an intra-hepatic pseudo-aneurysm after surgical correction of a thrombosed hepatic artery and its successful response to conservative management. Duplex Doppler ultrasound, associated with a new B-mode contrast-based sonographic technique, called "perfusional angiosonography", was used to diagnose the intra-hepatic pseudo-aneurysm. The combination of the two ultrasound techniques was useful in following the course of the pseudo-aneurysm, without further need for angiography. Eventually, this pseudo-aneurysm underwent spontaneous obliteration.