An analysis of hypersensitivity reactions to teniposide was approached using three methods: investigator survey, adverse drug reaction analysis, and literature search. By the survey method, hypersensitivity incidence was 6.5% with the majority of the reactions (82%) occurring in brain tumor or neuroblastoma patients. By the second method, 43 cases of hypersensitivity that were reported to the National Cancer Institute (NCI) between January 1983 and October 1985 were analyzed in detail. Reaction onset was unpredictable according to the number of drug doses. The majority of the patients (65%) experiencing the reaction had neuroblastoma or brain tumors, and these patients also tended to react earlier in the course of drug administration than those with hematologic malignancies. Clinical presentation was not correlated with the patient's diagnosis. All patients recovered. However, only six of 13 were successfully rechallenged with the drug. The third approach, the literature search, provided information on 82 hypersensitivity reactions among 2,250 patients (3.6% incidence). Forty-five percent of these reactions were linked to neuroblastoma or brain tumor patients. The analysis of hypersensitivity to teniposide by these three methods provides insight into the true incidence of hypersensitivity reactions in the general patient population. The frequency of the reactions is substantially higher in patients with neuroblastoma and brain tumors. This population should be considered for future trials of aggressive prophylactic therapy.