We report an unexpectedly high incidence of hypersensitivity to etoposide among 45 patients with newly diagnosed Hodgkin's disease treated with vinblastine, etoposide, prednisone, and doxorubicin (VEPA) plus radiation. Twenty-three of 45 patients (51%) had one or more acute hypersensitivity reactions to etoposide administration. The 23 patients were 8 to 18 years of age (median, 15 years); 12 were males. Four patients had experienced prior allergic reactions to antibiotics or intravenous contrast media. Hypersensitivity reactions followed the first or second dose of VEPA in most cases. The reactions occurred at a median time of 5 minutes (range, 3 to 120) from the start of the etoposide infusion. Fifteen patients reacted early (within 10 minutes), four midway through the infusion, and four after completion of the infusion. Signs and symptoms included flushing, respiratory problems, changes in blood pressure, and abdominal pain with or without nausea and vomiting. Respiratory problems included dyspnea, chest pain/tightness, bronchospasm, and cyanosis. Symptoms were alleviated by discontinuing the etoposide infusions and administering diphenhydramine and/or hydrocortisone; epinephrine was required to reverse bronchospasm in three cases. All 23 patients recovered without adverse sequelae and were rechallenged with etoposide. Fifteen patients tolerated subsequent etoposide infused at a slower rate, with antihistamine and/or corticosteroid premedication; five had recurrent hypersensitivity despite these measures. Three of these five developed similar symptoms when teniposide was substituted for etoposide. Three patients who had isolated episodes of hypotension on completion of the etoposide infusion successfully received subsequent infusions without premedication or change in infusion rate or concentration. Despite this unexpectedly high incidence of hypersensitivity among Hodgkin's disease patients treated with etoposide, rechallenge with the drug was successful in 78% of cases.