Due to developments in anti-retroviral treatment, young people with perinatally infected HIV are now surviving into late adolescence and adulthood. In addition to normative challenges presented throughout adolescence, HIV-positive adolescents must adjust to living with their diagnosis. There has been a considerable amount of research investigating how and when young people should learn of their diagnosis, and who should communicate this. Familial experiences of paediatric disclosure have been explored, however, limited studies have investigated familial HIV communication after this process. This Grounded Theory study aimed to explore the experience of HIV communication within the families of adolescents with perinatally acquired HIV following paediatric disclosure. It aimed to identify factors that facilitate or act as a barrier to HIV communication; how family members feel about HIV communication - or lack thereof - and its impact on wellbeing; and whether family members would like support in having discussions about HIV with each other. A final aim was to develop a model of familial HIV communication between adolescents and their biological mothers. Five adolescents with perinatally acquired HIV and their biological mothers were interviewed about their experiences. Data analysis led to a theoretical model of familial HIV communication following paediatric disclosure. The model comprised eight theoretical codes: (1) triggers to HIV communication; (2) barriers to HIV communication; (3) HIV topics that are up for discussion; (4) factors that influence HIV communication; (5) the experience of HIV communication; (6) the impact of HIV communication; (7) the role of others; (8) and the absence of sex communication. The findings highlight a number of suggestions for supporting families, and particularly mothers, with HIV communication. These are presented alongside possibilities for future research.