Abstract Background Good dental hygiene is strongly recommended for reducing the risk of developing infective endocarditis (IE). This is particularly important for patients with predisposing cardiac conditions (PCC), such as prosthetic valves, in whom the life-long risk of developing IE is much higher than in the general population. Despite this, the United Kingdom (UK) National Health System (NHS) only provides free dental care until the age of 18 years. Thereafter, adult patients enter a co-payment model, resulting in a large proportion not being able to access adequate dental care. Purpose To study the cost-effectiveness of providing free dental care to IE-high-risk patients in the UK. Methods A decision analytical cost-effectiveness model was designed as a combination of a Decision Tree (for a short-term model) and a Markov Model (for cost-benefit estimation in a long-term horizon). The costs and benefits (measured as quality-adjusted life-years or QALYs) of free dental care from the age of 18 years, or 50 years, in a high-risk population were assessed using NHS data. The cost of dental care reimbursement varies across the UK, from £18 to £162 per Unit of Dental Activity (UDA), depending on the Dental Practices contracts with the NHS. The cost of dental care used in the model was £26 per UDA, an average of the UK prices. In a co-payment scenario this translates into the NHS paying £4 and the rest of the cost being passed out to the patient. In a free dental care scenario, the NHS would pay the full £26. Results In a short-term horizon of 1 year, the model estimated that if 1 million high-risk patients were given access to free dental care, 638 cases IE (53 cases a month) and 95 deaths could be avoided each year. The cost of 1 death averted would be £142,926 (€162,208). The long-term model shows free dental care would translate into an extra cost of £66,687/QALY (€74,844) for the NHS if started at 18 years of age, or £96,287/QALY (€120,864) if started at 50 years of age. Conclusions Free dental care in patients at high-risk of IE is not cost-effective within the current willingness-to-pay (WTP) NICE guidelines (£20–30,000/QALY). This is significantly influenced by the elevated cost of dental care in the UK. If the UDAs were reimbursed as £18 homogeneously across the UK, the model results would be closer to the WTP threshold. Further studies are needed to explore alternative scenarios where this policy would be cost-effective. Transition state probabilities Funding Acknowledgement Type of funding source: None