This retrospective study evaluates our experience with clinically diagnosed nonocclusive mesenteric ischemia after cardiopulmonary bypass. Twenty-three of 3,600 consecutive patients suffered from splanchnic malperfusion. Symptoms developed between day 2 and 6 postoperatively in 18 of 23 patients. Four of 23 patients had no abdominal symptoms. Laboratory evaluation revealed significantly higher serum lactate and creatine phosphokinase levels in the 18 symptomatic patients compared with those of a control group. Arteriography was performed in 20 cases and revealed nonocclusive splanchnic hypoperfusion. Risk factors for development of mesenteric ischemia include arrhythmias and low cardiac output. Patients with angiographically proven nonocclusive mesenteric ischemia were treated with intra-arterial bolus injection and subsequent intra-arterial infusion of tolazoline combined with heparin sodium. The overall mortality rate was 30% (7 of 23). Infusion therapy with tolazoline and heparin seems to be a successful treatment modality for clinically diagnosed mesenteric ischemia.