Analgesics in patients with acute abdominal pain are often withheld for fear that they may change physical examination findings and thus may be unsafe. We conducted a randomized, prospective, placebo-controlled trial to investigate changes in physical examination following the administration of placebo, 5 mg, or 10 mg of morphine to 49 patients with acute abdominal pain. One patient was withdrawn secondary to inadequate documentation. Of the 48 patients who completed the trial, a statistically significant change in physical examination was noted in both groups receiving analgesics, but not in the placebo group. No adverse events or delays in diagnosis were attributed to the administration of analgesics. We conclude that physical examination does change after the administration of analgesics in patients with acute abdominal pain and that a larger study is needed to evaluate analgesic safety in this subpopulation of emergency department patients.