Importance::Several studies conducted worldwide (mostly in Western countries) highlighted the negative effects of problematic internet use, particularly among adolescents aged 12 to 17, including depression, impulsivity, aggression, and social fear and avoidance. In Lebanon, literature on the prevalence and impact of problematic internet use among adolescents is limited.Objective::This study aim was to study the association between problematic internet use and depression, impulsivity, anger, aggression and social phobia among Lebanese adolescents.Methods::A cross-sectional study was performed on 1103 young adolescents (14-17 years), recruited from October 2017 till April 2018. The Internet Addiction Test (IAT) was used to evaluate the level of problematic internet use. Data were analyzed using the MANCOVA analysis. The main independent variable of interest was the IAT, while the dependent variables included the psychological scales.Results::The multivariate analysis taking the psychological scales as the dependent variables and the problematic internet use (IAT score) as an independent variable, showed that problematic internet use was associated with higher depression, impulsivity, aggression, anger, hostility and social anxiety.Interpretation::Problematic internet use has become an important health issue that should not be overlooked, particularly because of the increased use of the internet by adolescents. Educational programs on early exposure to the internet should be developed.“,”Importance::Several studies conducted worldwide (mostly in Western countries) highlighted the negative effects of problematic internet use, particularly among adolescents aged 12 to 17, including depression, impulsivity, aggression, and social fear and avoidance. In Lebanon, literature on the prevalence and impact of problematic internet use among adolescents is limited.Objective::This study aim was to study the association between problematic internet use and depression, impulsivity, anger, aggression and social phobia among Lebanese adolescents.Methods::A cross-sectional study was performed on 1103 young adolescents (14-17 years), recruited from October 2017 till April 2018. The Internet Addiction Test (IAT) was used to evaluate the level of problematic internet use. Data were analyzed using the MANCOVA analysis. The main independent variable of interest was the IAT, while the dependent variables included the psychological scales.Results::The multivariate analysis taking the psychological scales as the dependent variables and the problematic internet use (IAT score) as an independent variable, showed that problematic internet use was associated with higher depression, impulsivity, aggression, anger, hostility and social anxiety.Interpretation::Problematic internet use has become an important health issue that should not be overlooked, particularly because of the increased use of the internet by adolescents. Educational programs on early exposure to the internet should be developed.