BACKGROUND: The OPTimisE intervention was developed to address uncertainty regarding the most effective physiotherapy treatment strategy for people with Lateral Elbow Tendinopathy (LET). OBJECTIVES: To assess the feasibility of conducting a fully-powered randomised controlled trial (RCT) evaluating whether the OPTimisE intervention is superior to usual physiotherapy treatment for adults with LET. DESIGN: A mixed-methods multi-centred, parallel pilot and feasibility RCT, conducted in three outpatient physiotherapy departments in the UK. METHOD: Patients were independently randomised 1:1 in mixed blocks, stratified by site, to the OPTimisE intervention or usual care. Outcomes were assessed using pre-defined feasibility progression criteria. RESULTS: 50 patients were randomised (22 Female, 28 Male), mean age 48 years (range 27-75). Consent rate was 71% (50/70), fidelity to intervention 89% (16/18), attendance rate in the OPTimisE group 82% (55/67) vs 85% (56/66) in usual care, outcome measure completion 81% (39/48) at six-month follow-up. There were no related adverse events. Patients and physiotherapists reported that the OPTimisE intervention was acceptable but suggested improvements to the trial design. 49 patients were recruited from physiotherapy referrals vs one from primary care records. Outcome measure return rates were higher when completed online (74%) compared to postal questionnaire (50%). Exploratory analysis showed improvements in both groups over time. CONCLUSIONS: It is methodologically feasible to conduct a fully powered RCT comparing the clinical and cost-effectiveness of the OPTimisE intervention versus usual physiotherapy treatment. Considering the similar improvements observed in both groups, careful consideration is needed regarding the priority research question to be addressed in future research.