Nomophobia is considered as the "disorder of modern world" and defined as "fear of being without access to a mobile phone." This study investigated gender differences in the relationship between problematic Internet use and nomophobia. Structural equation modeling (SEM) approach was employed to assess the relationship between nomophobia and four dimensions of the problematic Internet use, including diminished impulse control, loneliness/depression, social comfort, and distraction. The study used the Online Cognition Scale (OCS) and Nomophobia Questionnaire (NMP-Q) to collect data from 490 undergraduate students. Results indicated that loneliness/depression, distraction, and diminished impulse control were significantly related to nomophobia. However, there was not a significant relationship between social comfort and nomophobia. Further, multi group analysis results suggested notable gender differences in the relationship between problematic Internet use and nomophobia. The results for women indicated that loneliness/depression, diminished-impulse control, and distraction have a positive and significant relationship with nomophobia. Whereas only loneliness/depression and distraction were found to be significantly related to nomophobia among men. The results indicated a statistically significant difference in nomophobia and problematic Internet use between women and men subjects, where women subjects scored higher than the men.