Next to its well-known benefits, Internet may trigger harmful consequences due to its abuse, thus delineating clinical pictures that are similar to abuse disorders, such as Problematic Internet Use (PIU). The matter becomes more elusive for sportsmen, as data regarding PIU in this specific group are scarce, particularly for tennis players. Therefore, our aim was to assess the prevalence and the features of PIU in a sample of either in current activity or retired professional tennis players, as compared with healthy controls. Twenty-five professional tennis players were evaluated during two events held in two different European countries and were matched to an equal number of healthy subjects who were not performing any agonistic sport. The characteristics of Internet use were assessed by a specific instrument we developed (QUNT). Statistical analyses were carried out to evaluate both demographic and QUNT features and the possible intergroup differences. Retired athletes presented statistically significant lower scores compared to both athletes in current activity and control subjects in the "Time spent online" and in the "Addiction to pornography" domains. Athletes in current activity presented statistically significant higher scores compared to retired athletes in the "Ludopathy" and Total score domains. Male athletes had a statistically significant lower score in the "Addiction to pornography" domain compared to both female and male healthy controls. Tennis players frequently indulge in the use of Internet facilities, particularly those in current activity, thus potentially being more vulnerable to PIU. Men and women seem to use Internet for different activities. The lifestyle that professional tennis players are obliged to follow might provide an explanation of our findings.