BACKGROUND: Smartphone users frequently connect to the Internet via mobile data or Wi-Fi. Over the past two decades, the worldwide percentage of people who connect to the Internet using their mobile phones has increased drastically. OBJECTIVE: This study aimed to evaluate the potential link between mobile cellular data/ and Wi-Fi use and adverse health effects. MATERIAL AND METHODS: This cross-sectional study was conducted on 2,796 employees (52% female and 48% male) of Shiraz University of Medical Sciences (SUMS), Shiraz, Iran. The sociodemographic data (e.g., gender, age, nationality, and education level) were collected for all the participants. They were also requested to provide information about their smartphone use including the characteristics of the connection to the Internet using their smartphones (mobile data and Wi-Fi). In addition, the participants' history of diabetes, hypertension, cardiac ischemia, myocardial infarction, renal failure, fatty liver, hepatitis, chronic lung disease, thyroid disease, kidney stone, gall bladder stone, rheumatoid disease, epilepsy, and chronic headache was recorded through face-to-face interviews. RESULTS: 94% of people participating in this study reported using mobile/Wi-Fi internet. The mean (±SD) Internet usage per day was 117.85±122.70 minutes including 76±98 minutes of mobile data and 42±81 minutes of Wi-Fi use. CONCLUSION: Our findings showed no link between mobile phone Internet usage and the risk of the above-mentioned health problems. As in 2021, the global average daily time spent on the Internet using mobile phones was 155 minutes, the participants' lower use time could explain the failure to show any detrimental effects. Considering the study limitations, further large-scale studies are warranted.