We report on our experience in the use of transdermal fentanyl in management of acute pain due to mucositis WHO-grade IV during high-dose chemotherapy (HDC) and autologous stem cell support (APBSCT). Between 8/96 and 12/98 74 patients received HDC and PBSCT for progressive disease or relapse of non-Hodgkin's lymphoma (n=32), multiple myeloma (n=37), Hodgkin's lymphoma (n=5). All patients suffered from mucositis WHO-grade IV with a need for continuous pain management. Instead of pethidine i.v. fentanyl TTS was used. Sufficient analgesia was achieved mostly with a dose of 50 microg/h. There was no need of supplementary analgesia. Relevant fentanyl-associated side effects were not seen. Patient compliance and acceptance were excellent. The results suggest that transdermal fentanyl is reliable in pain management of chemotherapy-associated mucositis grade IV.