Pediatric patients with cancer are at high risk for severe infections and delayed treatment increases mortality. Infections can trigger changes of vital signs long before clinical symptoms arise. Continuous recording may detect such changes earlier than discrete measurements. This is the protocol for an investigator-initiated, single-center observational pilot study on the feasibility of continuous monitoring of health data with a wearable device (WD) in pediatric patients undergoing chemotherapy of cancer. A total of 20 patients will be included, including at least 4 patients <6 years. Each patient will wear the WD for 14 days and we expect study duration of three to four months. The protocol had been registered at www.clinicaltrials.com (NCT04134429) and was approved by the local Ethics Committees (Ethikkommission der Universitätskinderkliniken Bern, “Gesuch 1912”, Kantonale Ethikkommission Bern, BASEC-No.: 2019-01919).