Personalised health care is an evolution, moving away from a disease-focused model of care, translating scientific and technological advances into benefits for patients, and placing them at the centre of the patients' health and care. Companion diagnostics emerge as a very specific and special group of in vitro diagnostics among the different technologies shaping the personalised health care spectrum. Companion diagnostics provide highly valuable information, allowing patients, health practitioners and payers to decide with a higher level of certainty on the potential benefits of a treatment or care pathway. Decreasing uncertainty may result in a more efficient selection of treatments and care, targeted at subpopulations that are most likely to benefit. Companion diagnostics account for a minimal portion of the already small expenditure on in vitro diagnostics (far less than 1% of total health care expenditure), and yet they provide the means to limit inefficient use of health care resources while optimising patient outcomes. It is clear that equal access to personalised health care is still an issue across the EU. One of the most common perceived barriers is affordability. The investment in companion diagnostics can provide long-term value for patients and health care systems, shifting resources to areas of need. Health systems do not fully recognise yet the value that companion diagnostics bring to make personalised health care more affordable across the EU. This inhibits patient access to personalised treatments and care, preventing improved outcomes. In many countries, market access frameworks for diagnostic tests are fragmented and not aligned with specific funding and reimbursement mechanisms, discouraging the use of these tests. Emerging evidence shows that patients are missing out on the appropriate tests and treatments while a reduction in the inefficient use of health care resources is not realised. This article outlines some of these market access barriers for companion diagnostics in the EU, including reimbursement challenges specific to some member states (Germany, the UK, and France). Furthermore, proposals addressing barriers and increasing timely patient access to companion diagnostics in the EU are presented.