Background High serum CA19-9 is usually caused by pancreaticobiliary malignancies, but it has also been found in a tiny minority of calculous cholecystitis patients. Aims To clarify the relationship between calculous cholecystitis and serum CA19-9. Methods Clinical data of calculous cholecystitis patients with high serum CA19-9 (high group, n = 20) and normal serum CA19-9 (normal group, n = 40) who underwent cholecystectomy were analyzed. Serum CA19-9 of high group were followed-up and gallbladder specimens were analyzed by immunohistochemistry. Results Serum CA19-9 in the high group ranged from 105 to 1635 U/ml, of which 30% exceeded 1000 U/ml. Follow-up results showed that 20 patient’s serum CA19-9 returned to normal after cholecystectomy, including 4 closely followed-up patients whose serum CA19-9 recovered within one month. Immunohistochemical results revealed that CA19-9 was mildly positive only in mucosal epithelial cells in the normal group, but positive in mucosal epithelial cells, vascular endothelial cells, and intercellular substances in the high group, accounting for high serum CA19-9. Conclusion Serum CA19-9 is proved to be associated with calculous cholecystitis for the first time, so that clinicians should consider calculous cholecystitis associated CA19-9 elevation in the clinic practice besides other CA19-9 related diseases.