The utility of morphine-augmented cholescintigraphy was reviewed in 32 patients with suspected acute cholecystitis. All patients were administered 2 mg morphine sulfate intravenously when the gallbladder failed to visualize 30 minutes into the study, and imaging continued for up to 60 minutes. Sensitivity for detection of acute cholecystitis was 93% (13 out of 14). Specificity was 78% (14 out of 18). Three of four false-positives occurred in the setting of prolonged fasting and chronic cholecystitis. Cumulative experience suggests that the technique is diagnostically equivalent to imaging for up to 4 hours and that specificity remains incomplete in the setting of prolonged fasting, chronic cholecystitis and other conditions known to affect conventional cholescintigraphy.