According to recent studies, approximately a third of elite football players have visible tattoos on the field.1-4 The question whether tattoos on players would reflect dominance, extroversion, aggressiveness and willingness to take risks and thereby translate into notable behaviour patterns and field success is debated.1-5 Tattoos might be associated with individual performance or discipline,3, 4 but the impact on the overall team outcomes is unclear.3, 6 The success of a team is the result of a fine combination of personal skills, teamwork, opportunities and chance. The referee is the third major actor that must be considered. In this brief study, we reviewed the prevalence of tattoos among referees in four European football leagues during the 2021–2022 season, namely, La Ligue 1 (France), La Liga (Spain), Premier League (England) and Serie A (Italy). Referees' name, age and statistics were extracted from two websites (https://fr.whoscored.com and https://www.mondefootball.fr). Referees' visible tattoos (location, colours) were reviewed using the Getty Images website, with the same methodology as in our previous studies.1-3 For the tattoos, only the ‘visible’ tattoos were accounted for. ‘Visible’ tattoos were arbitrarily defined as those which could be seen on the field during official games or during trainings. They were either located: (i) on the head and neck, (ii) the upper limbs, from down the t-shirt sleeve at midpoint of the upper arm to the fingers and (iii) the lower limbs from the shorts to the socks. Getty Images Inc. is an American stock photo agency that supply stock images for business and consumers with an archive of 80 million still images and illustrations. We used the following keywords on the website's search bar: ‘Referee's full name and surname + name of the league + 2021 (or 2022)’. According to the referee, from one to over a hundred pictures could be found. A total of 112 referees were reviewed, but three were excluded because of a lack of available pictures. Among the 109 remaining, 108 were male (99.1%): forty-two were from Italy (39%, median 38.5 years), 25 were from France (23%, median age 39 years), 20 from Spain (18%, median age 40 years), 22 from England (20%, median age 42.5 years). Only two referees displayed visible tattoos on their upper limbs (1.8%), one from La Liga and one from Premier League. Both had very discrete tattoos that were hard to spot: one on the wrist but hidden by the wristwatch, and one whose tip could be noted was at the edge of the tee-shirt. Tattoo design could not be identified. With such a low number, we did not perform further analysis of referees' statistics. The prevalence of visible tattoos among referees from elite series is exceedingly low and homogenous between countries. Limitations of our study include that only visible tattoos on the field were collected. Referees may have hidden tattoos on the body (chest, back, shoulders, groins or feet). We may have missed small visible tattoos. Besides, some referees keep on upper long sleeves or large wrist bands all the time. Therefore, the prevalence of tattoos is most likely higher. However, our results are of interest. According to our previous studies among football players, the prevalence of visible tattoos among male football players is about 34%–36% during international1 or national competitions.3 There is an apparent dichotomy on the field between tattooed players and bare-skinned referees. However, the study has not been designed to address the reasons of such difference. Only online survey or structured interviews with referees would answer such a discrepancy. At that stage, we can only speculate on the underlying reasons. Age could be considered as a factor as referees are older than players.1, 3 However, they are mainly born between the end of the 1970s and the beginning of the 1980s and therefore belong to the generation that has embraced the trend of tattooing.7, 8 The sense of discipline and respect of rules that drive the referees might be associated with a reluctance to have visible tattoos. Referees would keep a distance from players by avoiding embracing their fashion trends. Referees are also bound to an image of discipline: for a long time referees have been dressed only in black. Lastly, arbitration bodies that allow referees to reach top-class levels may unconsciously (or not) accept rather those without visible tattoos. It is known that external factors may influence referees' decisions, as illustrated by the effect of matches played without spectators during coronavirus disease 2019 (COVID-19).9 Due to the very low prevalence of tattoos among referees, being tattooed may not affect referees' decisions on the field. Next work should now analyse whether tattoos on football players may influence referees' sanctions in case of fault. The author took fully part to conception of the work, acquisition, analysis, and interpretation of data for the work, drafted the manuscript and its final version; and he is accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Dr. Nicolas Kluger has received fees from Bioderma NAOS.