BackgroundThe pediatric patient-reported outcomes version of the common terminology criteria for adverse event measure was developed and validated for use in pediatric cancer clinical trials to better capture the symptom experiences through direct self-report. The study aim was to develop and validate a Swahili language version of the patient-reported outcomes version of the common terminology criteria for adverse event measure.MethodsThe pediatric version of 15 core symptom adverse events, and the corresponding questions, were selected from the patient-reported outcomes version of the common terminology criteria for adverse event library, then forward and back translated into Swahili by bilingual translators. The translated items were further refined using concurrent cognitive interviewing. Each round of interviews included five children, ages 8–17 years-old, receiving cancer therapy at Bugando Medical Centre, the cancer referral hospital for Northwest Tanzania, and continued until at least 80% of participants understood the question.ResultsThree rounds of cognitive interviews were completed involving 13 patients and 5 caregivers. Among patients, 50% of questions (19/38) were fully comprehended after the first interview round. Two Adverse Events (anxiety and peripheral neuropathy) were the most difficult for participants to understand, associated with education level and experience. Goal comprehension was achieved after three rounds of interviews with no further revisions required. All parents in the first cognitive interview group comprehended the survey, with no additional revisions.ConclusionA Swahili patient-reported outcomes version of the common terminology criteria for adverse event was effective in eliciting patient-reported Adverse Events related to cancer treatment, with good comprehension for children aged 8–17 years. This survey is important to incorporate patient self-reporting of symptomatic toxicities and is an effective tool to increase capacity for pediatric cancer clinical trials throughout East Africa, further reducing global disparities in cancer care.Supplementary InformationThe online version contains supplementary material available at 10.1186/s41687-023-00598-4.