INTRODUCTION: Febrile neutropenia (FN) episodes in sarcoma patients may be due to potentially life-threatening microbiologically defined infection (MDI). Clinical decision rules (CDRs) such as the Australian-UK-Swiss (AUS) rule have been developed to risk-stratify FN episodes, allowing for early discharge of patients at low risk of MDI. The AUS rule was validated in the multicentre Predicting Infectious Complications in Children with Cancer (PICNICC) FN episode dataset. However, similar paediatric CDRs perform poorly in teenage and young adult (TYA) cohorts, which comprise most young sarcoma patients. METHODS: Data were retrospectively collected for FN episodes of London Sarcoma Service patients aged 1-25 years diagnosed from 1 April 2020 to 31 March 2023. MDI rate was compared to the standard-risk (acute lymphoblastic leukaemia) patients in published PICNICC data. Sensitivity and specificity for likely bacterial infection (LBI) with 95% confidence intervals were calculated for an AUS score ≤1. RESULTS: A total of 157 patients met inclusion criteria (median age 15.4 years, range: 5.2-25.9 years). Outcomes were available for 159/160 FN episodes in 82 patients. IVADo had the highest rate of FN episodes per cycle: 23.5% [15.0%-34.9%] versus 18.8% [15.1%-23.1%] for MAP and 7.0% [5.4%-9.1%] for VDC/IE. Twenty-five of 159 (16%) FN episodes were blood culture-positive, significantly lower than standard-risk patients in the PICNICC dataset. The AUS score had a sensitivity of 62.9% [45.7%-78.2%] and a specificity of 29.8%[22.2%-39.0%] for LBI, with 13/35 (38%) LBI episodes missed. CONCLUSIONS: Overall, children and TYA with sarcomas are at lower risk of complications from FN, but the AUS rule performs poorly in this cohort. Better biomarker-driven CDRs are needed for risk-stratified FN management of these patients.