From November 1994 to May 1998, 117 patients (66 with solid tumor, 36 with lymphoma, 14 with multiple myeloma, one with acute leukemia) underwent 178 cycles of high-dose chemotherapy and autologous stem cell transplantation (ASCT) at our institution. We retrospectively analyzed the infectious complications that occurred after ASCT. Median duration of neutropenia (granulocyte count <0.5 x 10(9)/l ) was 8 days, the overall incidence of fever requiring antimicrobial treatment was 63%. 35.4% of patients had fever of unknown orign (FUO), whereas primary bacteremia occurred in 21.3%, pneumonia in 3.4% and severe skin infection in 1.1% of patients. Invasive fungal infections occurred in three, and enterocolitis in one patient. Infection was fatal in three patients (2.6%), in each case due to septic shock. The most frequently isolated pathogens were Gram-positive cocci. Median time to defervescence with antimicrobial therapy was 4 days (6 days in patients with bacteremia or other severe infection, and 3 days in patients with FUO). First-line antimicrobial therapy was successful in 65% of patients with FUO and 30.6% of patients with documented infections. With respect to the incidence, type and clinical course of infection, no significant differences between patients with lymphoma or multiple myeloma and those with solid tumors were detected.