BACKGROUND:The internet is an increasingly popular tool in family and child research that is argued to pose new ethical challenges, yet few studies have systematically assessed the ethical issues of engaging parents and children in research online. This scoping review aims to identify and integrate evidence on the ethical issues reported when recruiting, retaining and tracing families and children in research online, and to identify ethical guidelines for internet research. METHODS:Academic literature was searched using electronic academic databases (Scopus, PsycINFO, Embase, ERIC, CINAHL and Informit) and handsearching reference lists for articles published in English between January 2006 and February 2016. Grey literature was searched using Google to identify relevant ethical guidelines. RESULTS:Sixty-five academic articles were included after screening 3,537 titles and abstracts and 205 full-text articles. Most articles reported using the internet to recruit participants (88%) with few reporting online retention (12%) or tracing (10%). Forty percent commented on ethical issues; the majority did not discuss ethics beyond general consent or approval procedures. Some ethical concerns were specific to engaging minors online, including parental consent, age verification and children's vulnerability. Other concerns applied when engaging any research participant online, including privacy and confidentiality, informed consent and disparities in internet access. Five professional guidelines and 10 university guidelines on internet research ethics were identified. Few academic articles (5%) reported using these guidelines. CONCLUSIONS:Engaging families and children in research online introduces unique challenges requiring careful consideration. While researchers regarded themselves as responsible for ensuring research is conducted ethically, lack of use of available guidelines and limited academic literature suggests internet research is occurring without suitable guidance. We recommend broad dissemination of ethical guidelines and encourage researchers to report the methodological and ethical issues of using the internet to engage families and children in research.