Focus groups used for data collection in health research are increasingly conducted online. In two multi-center health research projects, we applied available methodological instructions for synchronous online focus groups (SOFGs). We describe necessary changes and specifications regarding the planning (recruitment, technology, ethics, appointments) and conduct (group composition, moderation, interaction, didactics) to enhance knowledge about the planning and conduct of SOFGs. Recruiting online proved to be challenging and necessitated direct and analogue recruiting, too. To ensure participation, less digital and more individual formats may be offered, e.g. telephone calls. Explaining verbally the specifics of data protection and anonymity in an online setting can foster participants' confidence to actively engage in the discussion. Two moderators, one moderating, one supporting technically, are advisable in SOFGs, however, due to limited nonverbal communication, roles and tasks need to be defined beforehand. Participant interaction is central to focus groups in general, but sometimes difficult to achieve online. Hence, smaller group size, sharing of personal information and moderators increased attention to individual reactions appeared helpful. Lastly, digital tools such as surveys and breakout rooms should be used with caution, as they easily inhibit interaction.