In this experimental study, after inducing mesenteric ischaemia in dogs, we investigated routine blood biochemistry, serum malondialdehyde (MDA) levels, histopathological changes and tissue MDA levels in the liver and intestines. The study group included 10 dogs. Six dogs which underwent sham operation served as controls. In the study group, the MDA level in liver tissue increased after superior mesenteric artery (SMA) ligation. Various degrees of necrosis were seen in the ileal biopsies 10 hours after the ligation. Hyperaemia and focal necrosis in the liver accompanied the intestinal necrosis if it was limited within the mucosa. However, massive or centrilobular necrosis was observed in the liver of those dogs which had intestinal necrosis that extended into muscular layers. MDA levels in intestinal tissue measured after SMA ligation were significantly higher than the preligation levels. On the other hand, the difference between serum and tissue MDA levels was not significant. The alterations in MDA were not significant in the sham group. Thus it is concluded that the serum MDA levels are valuable markers of diagnosis in intestinal ischaemia.