This study aimed at establishment of adequate evaluation of intestinal viability before release of the strangulated intestine by measuring electrical properties. In rats a 20-cm segment of the distal ileum and mesentery was strangulated. The intestine was strangulated for 0, 2, 15, 45, 90, and 120 min. The conductance and capacitance obtained by impedance analyzer were used to calculate tan(delta)m in the strangulated intestine. ATP was measured as well. In another experiment, after various periods of strangulation, tan(delta)m was measured just before release of the strangulation. Rats were divided into Group A (survived for 7 days) and Group D (died within 7 days). There was a positive correlation between tan(delta)m and ATP levels (P < 0.01). And tan(delta)m was significantly greater in Group A than in Group D (P < 0.05). There were no deaths at a tan(delta)m value of 2.36 or more and no survivors at a tan(delta)m of less than 2.20 except for one rat. These results suggested that tan(delta)m may be a useful index of the viability of the strangulated intestine before reperfusion.