Case 1, a man in his 70s, was admitted because of a bleeding gastric ulcer during DCF therapy for esophageal cancer(EC). Three days after endoscopic hemostasis, abdominal pain and vomiting occurred.CT revealed hepatic portal venous gas (HPVG).No intestinal necrosis was observed on contrast-enhanced CT.Therefore, we selected a conservative treatment and found improvement.Case 2, a man in his 70s, developed frequent diarrhea during DCF therapy for EC.Case 3, a man in his 80s, developed hematochezie during DCF therapy for EC.Both cases 2 and 3 were diagnosed as HPVG using abdominal ultrasonography.The symptoms were mild, so we selected a conservative treatment and found improvement.Case 4, a man in his 60s, noticed sudden severe abdominal pain during DGS therapy for EC.Plain CT detected HPVG and gas in the small intestinal wall.We suspected intestinal necrosis due to HPVG with peritoneal irritation and performed emergency small intestine resection.We encountered 4 patients who developed HPVG during chemotherapy.The presence of HPVG is a poor prognostic sign, suggestive of intestinal necrosis, but some patients show improvement with conservative treatments.We also discuss previous reviews and reports.