Background One of the core ethical principles in the Norwegian welfare state is the principle of justice; all citizens should have equal access to healthcare services, including nursing homes, independent of where they live, socioeconomic status or age. Patients who apply for a permanent place in a nursing home are among society's most vulnerable. Hence, it is of great importance that the process of nursing home placement is just. The purpose of this study was to explore which criteria and values allocation of nursing home placements are built on, and whether the process is just. Methods The study has a qualitative design. Data were collected through individual interviews and observation. Executive officers in different municipalities who have the formal responsibility for the placements, and GPs and nurses on short-term wards in nursing homes were interviewed. In addition, one of the researchers observed meetings where allocation of municipal healthcare services was discussed. Results Healthcare personnel in primary health care mainly agree on which criteria are the most important in order to safeguard the principle of justice. However, some unintended and less highlighted factors could jeopardise the ideal of fair and just allocation. Some of these were organizational variations, variations in the municipalities' economy, variations in individual judgments and resourceful and strong-willed relatives. Conclusions Our study indicates that some of the weakest and most vulnerable patients in the Norwegian society are not treated equally. In order to safeguard the principle of justice, specific national criteria should be used in allocation of nursing home placements. However, national criteria are not enough. We suggest that in addition to guiding criteria, the unintended factors should be given more attention and focus on how to control them in a better way.