The ultrasonically activated scalpel is a high-frequency oscillating instrument that is reported to have a decreased dispersion of energy to surrounding tissues during use. To determine if this effect is beneficial and safe to surrounding tissue, it was used on anesthetized adolescent swine to dissect the portal vein from the pancreas, the renal artery and vein from the renal hilum, the ureter from the retroperitoneum, the aorta from the inferior vena cava and the common bile duct from surrounding tissue. Three-second contact to intestine and nerve roots was also performed. Wedge biopsy specimens of liver and spleen were performed. Dissection technique used was as described by the company. Structures were dissected with electrocautery using similar techniques for comparison. Tissues were harvested and placed in formalin for histological analysis. Dissection with the ultrasonically activated scalpel was simple, achieved excellent hemostasis, and did not appear to damage adjacent tissue. Microscopic analysis showed adventicial and media injury to vascular structures. The ureter and common bile duct demonstrated marked injury with regions of transmural coagulation. Nerve and small bowel did not appear to have much injury from the 3-second contact with the instrument. This study indicated that although the ultrasonically activated scalpel can ease dissection with good hemostasis, care must be taken to avoid injury to adjacent structures. Although its lateral energy dispersion may be less than that of cautery, it can still cause transmural necrosis to major structures.