The accurate diagnosis of acute lower abdominal pain continues to be a problem. In Israel, a diagnostic sign often sought as indicating pelvic peritonitis is a rectal temperature of greater than 1.0 C higher than the simultaneous oral temperature. We established that in each of the 20 emergency rooms surveyed both oral and rectal temperatures are measured as part of the admission procedure for patients with acute lower abdominal pain. The charts of three groups of 100 patients with acute lower abdominal pain were studied retrospectively. A rectal temperature of greater than 1.0 C higher than the oral was found in about 10% of each group. Both oral and rectal temperatures were raised in 56, 69 and 37% of each group, respectively. The rectal temperature alone was elevated in 8.5% of patients with appendicitis or pelvic inflammatory disease (PID), as well as in 6% of patients with undiagnosed abdominal pain. Oral temperatures alone were elevated in 4.5% of patients with acute appendicitis or PID and also in 13% of patients with undiagnosed abdominal pain. These differences were not significant. We conclude that the common Israeli practice of measuring both rectal and oral temperatures in patients with acute lower abdominal pain gives no more information than the measurement of either one.