Abstract Background A large number of primary school children have personal smartphones which enable them to communicate with lots of people and use social networks. However, social networking should not be accessible to primary school pupils due to existing age restrictions. Studies show that cell phones can be used to send offensive or sexual content to children or by them. This might have long-term effects on child's mental health and even provoke suicidal thoughts. While parents are able to control many aspects of children's life, we aimed to disclose parental attitudes towards use of mobile phones among children. Methods A total number of 619 parents of primary school children from middle-sized town of Lithuania participated in this study. Parents anonymously expressed their opinion to questions about personal cell phones usage among children. Distribution of participants was assessed according to social and demographic characteristics. Results Most of the respondents (79.8%) indicated that use of mobile phones might be harmful to children's health, 56.0% indicated that their children use social networks and every second child was registered by their parents (49.5%). Minority of the respondents (8.1%) thought that children (including children from other families) receive messages from strangers and communicate with them (2.1%). Similarly, very few of the respondents thought that children receive offensive (15.0%) or sexual (4.8%) content. Younger and lower educated parents registered their children to social networks more frequently (p-value less than 0.05). Lower educated parents more frequently indicated that offensive or sexual content can reach children via smartphones (p-value less than 0.05). Conclusions Majority of parents of primary school children thought that cell phones might be harmful to children's health but most of them did not pay attention to threats such as communication with strangers or transmission of sexual content. Key messages Only minority of parents of primary school children indicated communication with strangers or transmission of sexual content as threats induced by use of smartphones among children. Regardless that lower educated parents indicated awareness of content-related threats to children more frequently they registered their children to social networks more frequently as well.