<p>Intensive Care Unit (ICU) admission for very old patients involves complex, critical, and time-sensitive decision-making. In the very old, the chances of a satisfactory functional recovery are more limited, remaining life years are fewer, and the quality of life after ICU discharge is often reduced. Predicting outcome, ICU length of stay, and establishing a burden-benefit balance is clinically challenging. Understanding the value that very old patients place on functional outcomes and quality of life is paramount. However, the very old are often exposed to over-servicing and overly aggressive treatments, under-servicing due to ageism, or receiving care that conflicts with their goals or best interests. Shared decision-making (SDM) is a collaborative process between healthcare professionals and patients or proxies, aligning with the high value that many modern societies place on individual autonomy. Quality SDM has the potential to integrate the treatment team's knowledge and recommendations with patient preferences, thereby improving the appropriateness of critical care provided. SDM can be supported by a time-limited trial of intensive care. However, when resources are scarce and patient admission must be restricted through a triage process, initial decision-making excludes SDM, as the principle of autonomy is set aside in favour of justice and the fair distribution of limited resources. Similarly, when admission is deemed futile or care is potentially inappropriate, SDM is unsuitable. Avoiding ageism in this context is challenging and requires carefully considering the effects and biases of chronological and biological age on prognosis and triage decisions.</p>