Phlegmonous gastritis in an uncommon bacterial infection of the gastric wall, predominantly affects immunocompromised patients, with high mortality rates despite appropriate treatment. Various risk factors compromising gastric mucosal integrity have been described. Symptoms are typically nonspecific and may manifest as acute abdomen, therefore, imaging studies gain special value. Proper treatment requires appropriate antibiotic therapy and surgical intervention may be considered in some cases. Available literature on patients with oncohematological diseases or undergoing chemotherapy who develop phlegmonous gastritis, is limited. We present the case of a female patient with relapsed acute lymphoblastic leukemia who developed phlegmonous gastritis during the neutropenic period following chemotherapy.