Abstract Background/Aims There is some evidence that children and young people (CYP) with Juvenile Idiopathic Arthritis (JIA) who are overweight/obese have less favourable disease control and treatment outcomes. The aim of this study was to investigate any association between BMI and total number of immune modulation therapies used in CYP with JIA. Methods This was a retrospective observational study at a tertiary paediatric rheumatology centre. Cross-sectional data was captured in April 2022 from CYP receiving immunomodulation therapies for JIA. Data on diagnosis, treatments and weight/height at last routine follow-up was included. BMI was calculated for each patient and centile assigned using Royal College of Paediatrics and Child Health electronic BMI charts as follows: BMI ≥85th to 94th centile - overweight, ≥95th centile - obese, as per population monitoring British 1990 growth reference (UK90). Results 187 CYP were identified and 180 included (seven were excluded due to missing BMI data). Baseline demographic, disease and treatment data are summarised in Table A. 67% were female. Median (interquartile range (IQR)) age in years at diagnosis and follow-up was 4.3 (2.7, 8) and 11.9 (8.5, 14.4) respectively. At follow-up, 41.1% of CYP were either obese or overweight. The median (IQR) number of total immunomodulation therapies per patient according to BMI categories were: under/normal weight 2 (1, 3); overweight 3 (2, 3) and obese 3 (2, 5). The median (IQR) years of follow-up in under/normal weight, overweight and obese groups were 4.77 (2, 8.74); 5.27 (1.86, 7) and 5.5 (3, 9.1) respectively. Conclusion CYP that were overweight/obese received more therapies compared to under/normal weight. The high proportion (41%) of CYP in this study who were either overweight or obese is similar to prevalence (44.2%) for children in year six at school in this region. Corticosteroid use and limited physical activity is associated with inadequate control of joint inflammation and increased BMI but this data was not collected and is an important limitation, in addition to cross-sectional and retrospective study design. The overweight/obese group had longer follow-up and may have accumulated more therapies. Future research to evaluate optimal dosing of immunomodulation in CYP with high BMI is warranted. Disclosure K. Hartley: Grants/research support; NIHR BRC Internship. S. Jandial: None. F. McErlane: None. E. Sen: None. S. Sampath: None.