We present a case of 45-year-old male with acute phlegmonous gastritis (APG) based on a hemolytic group A Streptococcus. APG is a rare and often a potentially fatal disease, which is characterized by a severe bacterial infection of the gastric wall. Because APG is a rapidly progressive disease, it comes with high mortality rates. Patients with an early diagnosis may undergo successful treatment and have a survival benefit. As soon as the diagnosis of APG is suspected, aggressive and adequate antibiotic treatment in combination with surgical intervention should be considered.