This study aims to identify and analyse all the doctoral theses defended in Spain that refer to the concept of "internal communication" (hereinafter IC) over a period of 34 years from 1986 to 2019 (including both). It should be noted that not all of them are specialized in IC, but that some of them refer to the concept in some way. For this purpose, a descriptive and retrospective bibliometric analysis has been used, divided into three phases: 1) Search and identification in Dialnet Plus and TESEO; 2) Analysis of a total of (n= 81) theses; 3) Graphic representation with RStudio of the relationships between advisers and chairmen of the tribunal. For this, 30 variables distributed in three dimensions (work, research team and evaluation team) have been used. 32 universities are present (85,2% of them are state owned), of which the UCM (22,2%) is the most productive, followed by the UNAV, the ULL and the UAB (all with 6,2% each). If we analyse the origin of the theses by autonomous xommunities, Madrid (28,4%), Catalonia (14,8%) and Andalusia (12,3%) are in the lead. The most prolific decade is 2010-2019 (56,8%), especially 2016 with 12,3% and in terms of languages, the theses have been presented mainly in Spanish (92,6%), with English being almost anecdotal (3,7%). Its authorship is divided close to parity with 50,6% of women and 49,4% of men. It should be noted that there is individualism in management with 71,6% of sole advisers and an average of 1.3 advisers per thesis. In addition, there is a strong dispersion of advisers and a minimal relationship with chairpeople, as only 5,1% have repeated in the management and among them, only on one occasion, they have coincided with the same chairman. It is relevant to mention that 70,4% of the first advisers are men and 80% of the professionals who have occupied this function more than once are also men. In terms of the composition of the boards, the chairmen (76,5%), the secretaries (60,5%) and the male members (71%) are the most important, and once again the UCM is the university with the greatest presence. As might be expected, the terms most used in the theses' titles revolve around "communication" and "internal" with 82,7% and 50,6% respectively. Among the descriptors, "communication" decreases to 49,4% (although it is still the most repeated) but "internal" disappears completely. There is evidence of a great diversity of items in both questions, although it is important to emphasize the use of concepts such as "strategy", "information", "influence" or "behaviour" that demonstrate the direct link between IC and public relations. By way of conclusion, it can be stated that the production of theses on internal communication in Spain has experienced a boom in the last decade thanks to state owned universities and with the UCM as the main creative and evaluative entity. Among the academics of the discipline, the figure of Alfonso-Javier Fernández-del-Moral, professor at the UCM, stands out, with two theses supervised and seven evaluation panels (five presidencies, a secretariat and a membership). Although there are no gender differences in terms of their origin, it is evident both in the management and in the tribunals, where men take especial presence. There is also the almost inexistent connection between advisers and members of the boards, and among the boards themselves. For future research work in this field, it would be interesting to delve into the main sources cited in these theses or to analyse the methodologies and tools most commonly used in them. [ABSTRACT FROM AUTHOR]