Background: One of the radiological signs of acute arterial mesenteric ischemia (AMI) according to data of Multi-spiral Computed Tomography with angiography (MCTA) is pneumatosis intestinalis (PI). Taking into consideration absence of reliable information on the pathophysiology of PI, we performed a comparison of radiological data and morphological studies of the resected bowel wall segments. Material and methods: We analyzed MCTA images of 15 patients with arterial AMI (men-9, women-6; average age – 71.1±3.5 years (95% CI: 63.64–78.49). Results: PI was determined in all cases of AMI: type I (bubbly-like) was diagnosed more frequently (p<0.01) than type II (semilunar) and constituted 11(73.3%) vs. 4(26.7%) cases, respectively. During histological evaluation of bowel wall tissues, a number of particularities of these phenomena were revealed: (1) PI in all cases of AMI was associated with necrosis and desquamation of bowel mucosa; (2) morphologically they have a “honeycomb” appearance and are localized predominantly in perivascular areas; (3) the pattern of spreading – from mucosa to serosa layer, distinguish it from “benign” forms of PI. Also, it was determined that type I PI was associated with transmural necrosis of the bowel wall in 63.6% cases, whereas in type II PI – in 100% cases (p<0.05). Diagnostic value of this sign (PI) in arterial AMI constituted: Sе, Sp, PPV, NPV=100%. Conclusions: MCTA should be considered a method of choice for diagnosis of AMI. PI should be considered as a specific radiological sign of AMI. PI type II is associated in all the cases with transmural bowel wall necrosis.