Short chain fatty acid (SCFA) and enteric bacteria in enteric fluid of 26 patients with non-strangulated intestinal obstruction were investigated. Sixteen to 905 mg/L of SCFA was detected in all the samples and acetic, propionic and lactic acid were prominent in the fraction. Concentration of SCFA reached a peak around the time of operation and then gradually decreased, in most cases. It also gradually decreased with clinical improvement in conservatively treated cases. Cultures of these enteric samples revealed 10(4-11)/ml of SCFA producing bacteria. SCFA may be one factor related to inhibition of water and electrolytes absorption and lead to distention of the bowel.