The potential was tested of white blood cell count (WBC), haemoglobin concentration (Hb) and erythrocyte volume fraction (EVF) to differentiate between patients with acute mesenteric ischaemia (AMI), perforation of colon, perforation of peptic ulcer, and intestinal obstruction. The WBC in patients with AMI (18.95 +/- 6.88 10(3) ml-1) was significantly above the normal range (upper cut-off 11.0 10(3) ml-1; P < 0.0001). Other variables in the patient groups did not differ from those of healthy individuals. All variables were, however, different between patients with AMI and non-AMI (P < 0.001). Receiver operator characteristic (ROC) curves were constructed to define the optimal cut-off for each variable. Sensitivity and specificity of the variables were between 62% and 75%. Discriminant analysis of the variables classified 80% of the patients correctly into AMI and non-AMI groups.