Fifteen mongrel dogs underwent a left lateral non-anatomical partial hepatectomy using a carbon dioxide laser, diathermy or a surgical scalpel. An original prototype of a compact hand-held laser was used and its effects were compared with those of the other two instruments. An improved dry cat surface was achieved by placing a rubber snare proximal to the planned incision. While no significant differences in the blood loss or in the operating time were found among the experimental groups, the laser beam sealed vessels of up to about 6 mm in diameter without any complementary suture ligatures, which were needed in the other groups. Histological studies revealed less tissue trauma in the sections performed by the laser and only slight secondary inflammatory reaction.