Population aging is causing increases in the numbers of chronic diseases, with the consequent need for changes in health systems to better assist patients with chronic conditions. A narrative review was conducted in this study with the objective of analysing the scientific evidence on the care and assistance provided by Case Management Nurses (CMNs) to chronic patients in primary healthcare. A total of 15 articles published in English, Spanish, and Portuguese were selected in the following databases: PubMed, Embase, Cochrane Library, Scopus, Dialnet, Cinahl, and Web of Science. In total, 46.6% of the studies showed the assistance provided by CMNs for chronic pathologies. Most of the articles selected (80%) considered that the assistance offered by case management nurses in relation to chronic diseases is effective, enabling cost reductions, which supposes benefits at the economic and political levels. It was concluded that CMNs have proven to be efficient in caring for people with chronic diseases, improving the quality of life of these people and their caregivers; therefore, they have a fundamental role in the PHC.