Aspergillosis is a potential, severe, and usually early complication of liver transplantation. New promising strategies, such as detecting Aspergillus antigenemia, have been used for the diagnosis of aspergillosis in immunosuppressed patients, but the impact in solid organ transplantation is not well known. A case-control study in 260 adults who underwent liver transplantation from January 1994 to June 2000 was performed. A case was defined as any liver transplant recipient with a proven or probable diagnosis of invasive aspergillosis. Controls were defined as a liver transplant recipient without aspergillosis infection with a survival longer than two months after transplantation. Clinical and analytical variables, including Aspergillus antigenemia, were compared. A special analysis was performed in patients in whom late aspergillosis developed (after day 100 posttransplantation). Among 260 patients, invasive aspergillosis developed in 15 (5.6%). Median time from transplantation to aspergillosis in 13 patients with sufficient data for analysis was 126 days (range, 22 to 1117). Seven (54%) developed the infection after day 100 posttransplantation. Thirty-eight patients were used as controls. Antigenemia was available in nine of 13 cases and in 33 of 38 controls. By multivariate analysis, retransplantation (OR, 29.9 [95% CI, 2.1 to 425.1]), dialysis requirements after transplantation (OR, 24.5 [95% CI, 1.25 to 354]), and the presence of Aspergillus antigenemia in serum at any time point after transplantation (OR, 50.0 [95% CI, 3.56 to 650]) were independently associated to aspergillosis. In the subgroup of patients that developed late aspergillosis, cytomegalovirus infection (OR, 6.7 [95% CI, 1.0 to 42.5]) was the only independent factor associated. Hepatic and renal dysfunction predispose to Aspergillus infection in liver transplant recipients. Cytomegalovirus infection and increased immunosuppression favor invasive aspergillosis during the late posttransplantation period. Aspergillus antigenemia seems to be a good predictor of invasive aspergillosis.