Acute pancreatitis (AP) has been recognized as a presentation of patients with pancreatic carcinoma (PC). However, the natural history of patients with PC who present with AP as the first manifestation is largely unknown. The aim of this study was to determine the time between the presentation of AP and diagnosis of PC and what factors should alert the clinician to suspect underlying PC in patients with AP. Nineteen physicians completed the survey forms that encompassed 45 patients with a diagnosis of AP preceding a diagnosis of PC. Information included the patient's age, gender, race, conditions that could account for the AP, criteria for diagnosis of AP, severity of AP, criteria for diagnosis of PC, time between the diagnosis of AP and PC, pathology of the carcinoma, extension of the disease, treatment of PC, and survival after the diagnosis of PC. The study population consisted of 45 patients, 27 (60%) men and 18 (40%) women whose average age was 58 years (range, 32-89). Thirty-eight patients were Caucasian, five were black, one was Japanese, and one Arabian. The number of AP episodes before PC diagnosis ranged between one and 15 (mean + 2 SD). AP was mild in 40 (89%) and severe in five (11%). The time between the onset of AP and the diagnosis of PC averaged 34 weeks (range, 1-52). Symptoms on presentation of AP included abdominal pain 45 (100%), weight loss 15 (33%), and jaundice 3 (7%). CA 19-9 was available in 13 patients, eight of whom had levels >100 at the time AP was diagnosed. Abnormal imaging suggestive of PC was detected by ultrasonography in 17 patients, by computed tomography in 30, endoscopic retrograde cholangiopancreatography in 20, and endoscopic ultrasonography in three. Tissue diagnosis was obtained in 43 of 45 (96%) patients; by surgery in 25 patients, needle aspiration in 14, laparoscopy in one, autopsy in two, and lymph node in one. Pathology revealed adenocarcinoma in 37 patients, squamous cell carcinoma in two, undifferentiated carcinoma in two, islet cell in one, and cystadenocarcinoma in one. Surgical findings in 26 patients included 19 with a nonresectable lesion or metastasis and seven patients with resectable lesion for cure. Thirteen patients (28%) were alive 1 year after the diagnosis of PC. The patients had a mean of two (range, one to 15) episodes of AP before the diagnosis of PC, and this was associated with a delay of 34 weeks from AP to diagnosis of PC. Patients with PC who presented with AP were generally older than 50 years of age and the severity of the pancreatitis was mild. The survival rate of patients with PC who presented initially with AP was >25% at 1 year compared with 20% 1 year overall survival of patients with PC. AP seems to be an early presentation of PC and should be sought in patients with idiopathic pancreatitis.