Artificial nutrition (AI) is one of the most representative examples of coordinated therapeutic programs, and therefore requires adequate development and organization. The first clinical nutrition units (CNUs) emerged in the public hospitals of the Spanish National Health System (NHS) in the 80s and have gradually been incorporated into the departments of endocrinology and nutrition (DENs). The purpose of our article is to report on the results found in the RECALSEEN study as regards the professional and organizational aspects relating to CNUs and their structure and operation. Data were collected from the RECALSEEN study, a cross-sectional, descriptive study of the DENs in the Spanish NHS in 2016. The survey was compiled from March to September 2017. Qualitative variables were reported as frequency distributions (number of cases and percentages), and quantitative variables as the mean, median, and standard deviation (SD). A total of 88 (70%) DENs, out of a total of 125 general acute hospitals of the NHS with 200 or more installed beds, completed the survey. CNUs were available in 83% of DENs (98% in hospitals with 500 or more beds). As a median, DENs had one nurse dedicated to nutrition (35% did not have this resource). Fifty-three percent of DENs with nutrition units had dieticians integrated into the unit (median: 1). DENs located in hospitals with 500 or more beds are more complex and have a wide portfolio of monographic unit services (morbid obesity, 78.3%; artificial home nutrition, 87%; chronic diseases, 65.2%) and specific techniques (impedanciometry, 78%). However, only 14% of the centers perform universal screening tests for malnutrition, and a secondary diagnosis of malnutrition only appears in 12.3 reports per 1000 hospital discharges. After the 1997 and 2003 studies, the results of 2017 show a marked growth and consolidation of CNUs within the DENs in most hospitals. Today, the growth of this specialty is largely due to the care demand created by hospital clinical nutrition. CNUs still have an insufficient nursing staff and dietitians/nutritionists, and in the latter case, atypical contracts or grants funded by research projects or the pharmaceutical industry are common. Units for specific nutritional diseases and participation in multidisciplinary groups, quite heterogeneous, are concentrated in hospitals with 500 or more beds and represent an excellent opportunity for CNU development. Many DENs of Spanish hospitals include CNUs where care is provided by endocrinologists, who devote most of their time to clinical nutrition in more than half of the hospitals. This is most common in large centers with a high workload in relation to staffing. There is considerable heterogeneity between hospitals in terms of both the number and type of activity of the CNUs. Copyright © 2020 SEEN y SED. Publicado por Elsevier España, S.L.U. All rights reserved.