From September 1984 to August 1991, 48 evaluable patients with resected gastric cancer and apparent disease confined to locoregional area were treated with intraoperative electron beam boost to the celiac axis and peripancreatic nodal areas (15 Gy) and external irradiation (40 to 46 Gy in 4 to 5 weeks) including the gastric bed and upper abdominal nodal draining regions. At the time of evaluation for IORT, the disease was primary in 38 cases, recurrent but resectable in four (anastomosis), and unresectable in four (nodal). Post operative complications were reversible. Acute tolerance to the complete treatment program was acceptable. Late complications included life-threatening events: Six episodes of gastro intestinal bleeding (three of them had an arteriographic documentation of arterioenteric fistula) and nine with severe enteritis (five required reoperation). Other long-term treatment related complications were six cases of vertebral collapse. The median follow-up time for the entire group is 22 months. Locoregional recurrence/persistence of disease has been identified in five patients (three with residual and/or recurrent postsurgical tumor). Systemic tumor progression has been detected in 15 patients (11 in intra-abdominal sites). Overall actuarial survival for patients with positive or negative serosal involvement was 33% versus 56%. It is concluded that the treatment program described is able to induce a high locoregional tumor control rate (100%) when used strictly in an adjuvant setting and might control long term, a small portion of patients not amenable for curative surgery (2 out of 8 patients with confirmed residual post-surgical disease). Gastrointestinal bleeding and enteritis are findings that indicate treatment intensity at the upper limits of tissue tolerance. Assessment of long term tolerance of pancreatic parenchyma and large blood vessels (tissues included in the IRORT field) are pending for longer follow-up and the appropriate selective studies.