Tobacco is the leading preventable cause of death globally, causing approximately 7 million deaths each year. No ethical standard exists to guide researchers considering their obligation and ability to provide treatment for study participants who use tobacco. We propose that tobacco cessation treatment should be offered as ancillary care to interested study participants who use tobacco. We share a case study in which we describe our approach to implementing a brief behavioural tobacco cessation intervention as part of an observational study of tobacco use patterns in South Africa.