The quantification of referees’ loads is playing an increasingly important role in the scientific field thanks to the professionalisation and advances achieved by referees. The aim of the present paper consists in analysing the relations between their internal (objective and subjective) and external load parameters. The sample was composed of a total of 15 matches played in the women’s U16 Eurobasket championship, in which a total of nine referees (6 men and 3 women) participated. The internal load variables analysed were heart rate (%HRmax) and the subjective rating of perceived exertion (RPE). The external load variables were divided into kinematic (accelerations, speed and distance) and neuromuscular (Player Load, Metabolic Power and Impacts) variables, measured using inertial devices. The results show that there are associations between the values of objective internal load and external load, as well as between the variables of external load. In contrast, there is no relation between internal subjective load (RPE) and the variables of objective internal and external load, except regarding Metabolic Power. These results indicate that the competition and the level of the referees greatly influence the subjective variables. Moreover, it is necessary to be familiar with different methods for measuring referees’ performance indicators for them to be able to adapt to the needs and possibilities offered by the competitive context.