Liposomal amphotericin B (AmBisome) was used for suspected or confirmed fungal infection complicating 133 neutropenic episodes in 116 patients not tolerating, or not responding to, conventional amphotericin. Adverse effects were infrequent and no significant renal impairment resulted. Acute reactions occurred in five patients, reversible hepatic dysfunction in 23, and hypernatraemia in 17. The putative mycosis resolved with AmBisome treatment in 81 episodes (61%) and progressed with fatal outcome in 25 (19%), but the diagnosis was equivocal in most, and in 27 episodes (20%) evidence indicating nonfungal pathogenesis emerged. Treatment efficacy is, however, evaluable in those with proven aspergillosis. 13/17 patients with confirmed invasive aspergillosis responded to AmBisome (77%), conventional amphotericin having failed in 11. Treatment was successfully discontinued when the neutrophil count was < 1 x 10(9)/l in eight responders (61%). In four further patients treated for suspected aspergillosis, disseminated infection was documented at post-mortem, but the true incidence is unknown. This analysis confirms that AmBisome is well tolerated and effective against invasive mycoses in neutropenic patients, and may salvage patients when conventional amphotericin proves excessively toxic or ineffective.