AbstractFever in neutropenia (FN) is the most frequent potentially lethal complication of chemotherapy in patients with cancer. The temperature limit defining fever (TLDF) for FN is based on scarce evidence. This prospective, single center observational study recruited non-selected pediatric patients diagnosed with cancer between ≥1 and ≤17 years in 2012 and 2013. Of 40 patients potentially eligible, 39 participated. Data of 8896 temperature measurements and 1873 complete blood counts (CBCs) were recorded over 289 months (24.1 years) of chemotherapy exposure time. During this time 43 FN episodes were diagnosed. In 32 episodes, FN diagnosis was based on reaching the local (i.e. Bern, Switzerland) standard TLDF of 39.0 °C; another 11 episodes had been captured by clinical judgement (i.e. temperature < 39.0 °C). These data can be used to simulate the effects of various TLDFs on the rate of FN diagnosis. We assume merging these data with other data sets is feasible.