The National Health Service is poised to offer at least one cycle of IVF treatment to couples free of charge in the UK, provided that certain clinical criteria are met. At a local level, therefore, funders are faced with the problem of prioritizing patients and establishing waiting lists. It is generally accepted that preference should be given to those with the ‘greatest need’, but it is uncertain what the criterion is for greatest need. We propose two recommendations as a modification to the current guideline that stresses the need to favour ‘couples who do not have any children living with them’. First, we suggest that parental responsibility rather than shared residence be used as a criterion for eligibility. Second, we present a need-based approach that can be used coherently to distribute publicly funded treatment. In an attempt to achieve a fair way of prioritizing patients, we make distinctions between different family arrangements, based on the number of existing children. Our approach treats like cases alike, and ranks different cases relative to each other in a manner that is equitable and charitable.