To analyze the feasibility of involved-field irradiation (IFI) in patients with locally advanced adenocarcinoma of gastroesophageal junction (AEG) in Siewert’s type II and III underwent preoperative concurrent chemoradiotherapy. A total of 45 cases were involved into this study. Patients received two cycles of chemotherapy with XELOX and concurrent radiotherapy (45Gy/25f, five fractions per week). After 6 to 8 weeks, they underwent operation. Patients were filled with 800 to 1000 ml water before CT simulation, and more than 5mm of stomach wall on the CT images was delineated as GTV-primary, with the reference of upper gastrointestinal barium meal, esophagus endoscopy, and MRI simultaneously. CTV provided a proximal margin of 2.0cm and distal margin of 1.5 to 2.0cm and radial of 0.8cm around the GTV-primary. GTV-nd was drawn on each relevant slice of the planning CT, and we just regarded GTV-nd and its involved area of metastasis (IFI) as CTV-nd. PTV was defined as 0.8 to 1.0cm of external expansion. The feasibility of IFI was analyzed via the postoperative pathology response and toxicity of chemoradiotherapy. Of the 45 patients, 39 completed preoperative concurrent chemoradiotherapy (CCRT), 6 underwent one cycle of chemotherapy with irradiotherapy. The R0 resection rate was 93.3% (42/45). The rate of pathological complete response (pCR) was 22.2% (10/45). The patients with tumor regression grade 0 to grade 3 were 10 (22.2%), 17 (37.8%), 15 (33.3%), 3 (6.7%), respectively. The lymph node metastasis rate and ratio were 37.8% (17/45) and 4.3% (46/1062). After neoadjuvant chemoradiotherapy, down-staging of T and N were observed in 24 and 26 patients, respectively. The proportion of pathological of stage T3∼4 had a decline by 51.1%, N positive by 42.2%, and stage III-IV by 37.8% (c2=30.896, P=0.000, c2=16.568, P=0.000, c2=17.822, P=0.000). The incidence of esophagitis/gastritis was 44.4% (20/45), and grade 1-3 were 17.8%, 22.2%, 4.4%, respectively. The rate of grade 1-2 pneumonitis was 6.6% (3/45). One patient died of treatment toxicity. A total dose of 45Gy irradiation with concurrent 2 cycles of XELOX regiment before surgery for locally advanced AEG with Siewert’s type II and III could achieve a preferable pCR and higher R0 resection. The rate of lymph node metastasis is decreased obviously, as well as T and N stage. In addition to mild toxicity, concurrent chemotherapy with IFI is worthy to be studied further.