Despite its wellknown adverse effects, Amphoterin B is an integral part of any supportive therapy in haematology/oncology. We report on a thirteen year old boy with acute myelogenous leukemia and suspected fungoid pneumonia. Shortly after iv or inhalative application of Amphotericin B he repeatedly presented with a Raynaud phenomenon of his toes, which ceased after switching to Ambisome (liposomal unilamellar encapsuled Amphotericin B). Since there is evidence that thromboxane A2-mediated arteriolar spasms of renal vessels provoke the wellknown increase in serum creatinine after Amphotericin B, and in different species pulmonal vasoconstriction has been observed, we speculate that a similar mechanism is responsible for the observed Raynaud phenomenon. Thus we suggest inhibitors of prostaglandine synthesis for therapy.