Appendicitis has rarely been reported following solid organ transplantation and never following liver transplantation. We reviewed records of all patients who received solid organ transplants at UCLA between 1989 and 2002 and subsequently underwent appendectomy for presumed acute appendicitis. Of nearly 8000 transplant patients, 17 (nine male, eight female) subsequently underwent appendectomy for presumed acute appendicitis. Average age at appendectomy was 37 yrs (range 6-73 yrs). Organ transplants included liver (seven patients), heart (four), kidney (three), kidney-pancreas (two), and heart-kidney (one). The mean interval from transplant to appendectomy was 1064 d (16-2977). Presenting symptoms and signs included abdominal pain in 16 patients (94%); nausea and or vomiting in 15 (88%); right lower quadrant tenderness in 16; and leukocytosis (WBC > 10 000) in 13 (76%). Mean interval from presentation to appendectomy was 0.94 d (range 0-4). Computed tomography (CT) was performed in 16 patients and showed signs of acute appendicitis in 15. Open technique was used in all patients, preceded by laparoscopy in one. Pathology showed appendicitis in 15 patients (one with perforation), serositis in one, and a normal appendix in one. Mean duration of hospitalization was 7 d (range 1-20). Complications occurred in four patients (24%) and included intra-abdominal abscess requiring percutaneous drainage, ventral hernia, small bowel obstruction, and hematuria in one patient each. There were no deaths and no cases of acute rejection during hospitalization. Average length of follow-up was 712 d (range 3-2492). We conclude that appendicitis is relatively rare following solid organ transplantation. CT facilitates prompt diagnosis. The clinical presentation is similar to that of non-transplant patients, but complications are more frequent, and hospitalization is longer.