Background: Adolescents are vulnerable to both mobile and internet addiction. In Arab countries studies on both types of addiction are scarce. Objectives: This study aimed at comparing the prevalence of problematic mobile and internet use among Egyptian and Saudi adolescent females. Methods: A cross sectional study which included 538 Saudi and 802 Egyptian adolescent female students. A questionnaire was used to collect data about patterns of mobile phone and internet use. Young Internet Addiction Test (YIAT) and the Mobile Phone Addiction Scale (MPAI) were also used. Results: Saudi students showed higher rates of mobile (11.7%) and internet addiction (5.8%) compared to Egyptian students (6.1% & 1.6% respectively). They also had higher number of calls, longer time of internet use and more frequent internet use per week. A significant weak positive correlation was found between YIAT scores and MPAI scores. Conclusion: This study indicated the need for future studies to address the related risk factors of both problems among adolescents in both countries