Physical exercise is a safe, cost-efficient, and effective intervention for cancer survivors. Regular exercise can reduce symptoms such as cancer-related fatigue, depression, prevent and reduce co-morbidities, attenuate toxicity related to cancer treatment, and reduce cancer-specific and all-cause mortality 1-4. Exercise is generally recommended for all cancer survivors and should be started as early as possible 5. However, there is limited evidence in head and neck cancer (HNC) 6, which has multiple challenges; patients typically present with substantial weight loss, inactivity and low cardiorespiratory fitness; treatments are gruelling with substantial short and long-term symptom burden; many live in areas of high deprivation, residing some distance from their treating centre and have low levels of health literacy; integrating interventions to this complex care pathway is challenging 7-13. Objective: To investigate the feasibility of introducing a remotely delivered, personalised, collaborative, and flexible exercise programme into the HNC care pathway. This prospective single arm feasibility and acceptability study aimed to recruit seventy HNC patients from two UK Centres, over 12 months. A conservative retention rate of 60% was predicted, to provide a minimum of 42 patients on study completion. The intervention was a personalised 8-week exercise programme delivered remotely by cancer exercise specialists, trained in behaviour change techniques. Patients were invited to participate any time between diagnosis and 8 weeks post-treatment, according to their preference. Intervention content was based on patient needs, preferences, and goals, guided by physical activity cancer guidelines. Primary outcomes included recruitment and retention. A qualitative sub-study included patient and healthcare professionals semi-structured interviews to evaluate intervention experiences and processes. One hundred and eighteen patients were eligible for the study, 107 patients were approached, and 76 consented (71%). Recruitment uptake was different for each site 54% vs 82%. Reasons for non-participation were; too much to think about, additional paperwork, uninterested in exercise. Participants M:F ratio 3:1; mean age 60.5 years (range 34-80). The majority had oropharyngeal (54%) or oral cancer (33%), 56% had T1/2 tumours. Fifteen patients (19%) had over the recommended alcohol intake (14 units/week), 8 (10.5%) were current smokers. Treatment included surgery alone (28.8%) surgery and adjuvant (chemo)radiotherapy (50.0%) or primary (chemo)radiotherapy (21.2%). The majority of patients consented to ACTIOHN pre-treatment (45%). Data collection finishes in February 2024. To date, 32 patients have completed ACTIOHN, 27 are on treatment and 17 have withdrawn. Key themes from on-going patient interviews (N=17) are; therapeutic alliances; understanding what the intervention involved; personalisation; treatment impact; programme impact; paperwork, and from eight healthcare professionals; describing the programme; personalisation; nutrition; treatment impact; buy-in. This high uptake indicates that the ACTIOHN intervention was acceptable to HNC patients. Overall patients and HCPs were positive about the intervention. However, there were substantial system challenges, and despite many consenting to participate pre-treatment, a proportion of surgical patients were unable to start ACTIOHN until post-treatment. Patients appreciated a strong therapeutic bond and tailoring of the intervention to their needs and preferences. ACTIOHN requires further investigation to test effectiveness and fit with the pathway.