In 2014, Stockholm became the first Swedish county to introduce the rotavirus vaccine, which is given from as early as six weeks of age. The aim of this study was to describe parental conceptions of rotavirus infection and vaccination during its implementation as part of the child immunization program, as their support is vital for any new vaccine. The study followed a descriptive, qualitative design with a phenomenographic approach. Ten in-depth interviews with parents were conducted in Stockholm County, transcribed and analyzed to describe qualitatively different conceptions of rotavirus infection and vaccination. Four main categories were identified: to vaccinate without doubt, hesitant to vaccinate, risky to vaccinate, and unnecessary to vaccinate. All the parents had in common the desire to protect their children from suffering, either by vaccinating their child in order to avoid rotavirus infection or by not vaccinating their child because of concerns about the side effects. It is important that child health-care professionals understand the variations of conceptions that influence the parents' decisions and that these conceptions may differ considerably. Individualized parental information about rotavirus infection and vaccination would help to achieve a successful implementation of the vaccination program.