We report the occurrence of invasive aspergillosis (IA) in nonallografted patients with multiple myeloma (MM) who were treated at hematology or oncology centers in Europe during 1984-1996. Thirty-one cases met the criteria for definitive (21 [68%]) or probable (10 [32%]) IA. Of these cases, 23 (74%) were reported during 1992-1996. Twenty-nine cases (94%) occurred in patients with Durie-Salmon stage 3 MM, and 2 (6%) occurred in patients with Durie-Salmon stage 2 MM. The median time between MM and IA diagnoses was 8 months (range, 1-75 months). Sixteen patients (51%) had a neutrophil count </=500/mm3 for a median duration of 19 days (range, 10-37 days). Fourteen patients (45%) had recently received corticosteroid therapy, and 11 (36%), high doses of melphalan. Twenty-eight patients had primary pulmonary IA, and 3 had primary sinus IA. Forty-five percent of patients were considered to have died of IA. IA occurs as a potentially lethal opportunistic infection in intensively treated nonallografted patients with myeloma.