OBJECTIVES--(a) to determine the efficacy of papaveretum in treating pain when administered early to patients presenting with acute abdominal pain and (b) to assess its effect on subsequent diagnosis and management. DESIGN--Prospective, randomised, placebo controlled study. SETTING--Walsgrave Hospital, Coventry. SUBJECTS--100 consecutive patients with clinically significant abdominal pain who were admitted as emergencies to a surgical firm. INTERVENTIONS--Intramuscular injection of up to 20 mg papaveretum or an equivalent volume of saline. OUTCOME MEASURES--Pain and tenderness scores, assessment of patient comfort, accuracy of diagnosis, and management decisions. RESULTS--Median pain and tenderness scores were lower after papaveretum (pain score 8.3 in control group and 3.1 in treatment group, p < 0.0001; tenderness score 8.1 in control group and 5.1 in treatment group, p < 0.0001). Forty eight patients were deemed to be comfortable after papaveretum compared with nine after saline. Incorrect diagnoses and management decisions applied to two patients after papaveretum compared with nine patients after saline. CONCLUSION--Early administration of opiate analgesia to patients with acute abdominal pain can greatly reduce their pain. This does not interfere with diagnosis, which may even be facilitated despite a reduction in the severity of physical signs. These patients should not be denied effective treatment.