Thirty cases with MRSA in the sputum (carrier state) were studied in relation to fecal MRSA detection. The back ground of the cases (disease, nasogastric tube, tracheostomy, antibiotics, H2-blocker) and typing of MRSA (coagulase type, Pulse Field Gel Electrophoresis (PFGE) type), and gastric pH were studied. Almost all of the patients were given antibiotics of the cephem series of the third generation. None of the cases had abdominal operations. Fecal MRSA was positive in 14 cases (47%). H2-receptor antagonists (H2-blocker) was administered to 6 cases, and all cases (100%) had positive fecal MRSA. Eighteen cases had a history of H2-blocker administration and 5 cases had positive fecal MRSA. Duration after stopping the H2-blocker in the 5 cases was shorter than the other 13 cases. (4.5 to 20.8 months). Nasogastric tube had no significant effect in detection of fecal MRSA. And gastric pH was of no significant difference between MRSA positive cases and negative cases. These results suggest that in patient with MRSA in the sputum receiving a H2-blocker may produce MRSA enteritis because of MRSA passage to the stomach.