BackgroundAvoidant/restrictive food intake disorder (ARFID) prevalence in children with gastroparesis (Gp) and/or functional dyspepsia (FD) is unknown. We aimed to identify ARFID prevalence and trajectory over 2 months in children with Gp, FD, and healthy children (HC) using two screening questionnaires. We also explored the frequency of a positive ARFID screen between those with/without delayed gastric emptying or abnormal fundic accommodation.MethodsIn this prospective longitudinal study conducted at an urban tertiary care hospital, patients ages 10–17 years with Gp or FD and age‐ and gender‐matched HC completed two validated ARFID screening tools at baseline and 2‐month follow‐up: the Nine Item ARFID Screen (NIAS) and the Pica, ARFID, and Rumination Disorder Interview‐ARFID Questionnaire (PARDI‐AR‐Q). Gastric retention and fundic accommodation (for Gp and FD) were determined from gastric emptying scintigraphy.Key ResultsAt baseline, the proportion of children screening positive for ARFID on the NIAS versus PARDI‐AR‐Q was Gp: 48.5% versus 63.6%, FD: 66.7% versus 65.2%, HC: 15.3% versus 9.7%, respectively; p < 0.0001 across groups. Of children who screened positive at baseline and participated in the follow‐up, 71.9% and 53.3% were positive 2 months later (NIAS versus PARDI‐AR‐Q, respectively). A positive ARFID screen in Gp or FD was not related to the presence/absence of delayed gastric retention or abnormal fundic accommodation.Conclusions & InferencesARFID detected from screening questionnaires is highly prevalent among children with Gp and FD and persists for at least 2 months in a substantial proportion of children. Children with these disorders should be screened for ARFID.