Vascular diseases in oncology are often attributed to several factors (hospitalisation, paraneoplastic syndrome, probable damaging effect on epithelium by chemotherapeutic agents) however they are reasonably infrequent events. From 7/10/1993 to 21/3/1994 we observed 8 cases of vascular diseases (venous and arterial) of varying intensity in patients receiving anticancer chemotherapy in association with third generation antiemetics. On the basis of similar experiences reported in the literature of patients undergoing chemotherapy and serotonin-antagonist antiemetics, we performed a detailed analysis of these 8 cases. Few-cases of vascular diseases have been observed in phase II and III studies inpatients treated with ondansetron but the physiopathological mechanism is still not well understood. Of our 8 patients, 5 were female and 3 male, with ages ranging from 36 to 73 years. All cases had different types of solid tumors and had been treated with different chemotherapeutic schemes (two containing cisplatin). All the patients had received varying doses (from 16 to 96 mg for 5 days) of ondansetron. Vascular complications occurred 1 to 3 weeks after treatment and 3 cases are still receiving therapy. It can be noted that two patients who had previously been treated with ondansetron did not develop vascular problems. This drug has been in use in our department since May 1991, but problems of a vascular nature only arose in October 1993. At present a final conclusion cannot be reached as to the link between ondansetron and vascular complications.