Many international studies in the field of Internet use and Problematic Internet Use (PIU) have shown strong and frequent relationships with psychopathology. However, few researches have investigated the relationships between PIU and personality variables such as defense, coping and pathological traits. The aim of the present study was to explore the rate of PIU among French users and its relationships with psychopathological (depressive symptoms, self-esteem, pathological personality traits) and psychological variables (defense mechanisms and coping strategies). A sample of 786 participants, aged between 18 and 35 years old (M = 23.7; SD = 4.5) has been recruited online and completed several scales assessing PIU, time spent online, socio demographic, psychological and psychopathological variables. More than 20% of the sample had PIU. Compared to non-problematic users, they had significant higher scores of all personality disorder clusters, non-adaptive coping and depressive symptoms. Among the total sample, PIU was predicted by Clusters B and C personality traits, immature and autistic fantasy defense styles, non-adaptive coping strategies and depressive symptoms. Significant gender differences have been retrieved. Psychological and psychopathological variables, including personality traits should be further explored, and gender differences always taken into account when assessing PIU.