The purpose of this study was to observe electromyographic activity of stomach, small bowel, and colon during and early after identical laparoscopic and conventional operations to compare the operative trauma. In nine dogs a cholecystectomy was performed laparoscopically (n = 5) or by laparotomy (n = 4). Analysis of electromyographic activity focused on rhythm, frequency, and amplitudes of slow waves. Furthermore, oxygenation of blood and tissue, intestinal impedance, intraabdominal humidity, and temperature were documented to investigate their influence on slow waves. Open cholecystectomy caused an evident decrease of frequency and amplitude of co-Ionic slow waves in comparison to laparoscopic cholecystectomy. Arrhythmic slow waves were observed only in the stomach during conventional cholecystectomy. Stomach and small intestine showed no significant difference of frequency and amplitude of slow waves in both operation groups. Intraabdominal humidity and intestinal impedance differed significantly in laparoscopy and laparotomy. Laparoscopic cholecystectomy proceeded with a minor abdominal trauma documented by smaller alterations of slow waves. This may be caused by reduced peritoneal desiccation.