Introduction: Children living with HIV rely on adult caregivers for access to HIV testing and care, including clinical monitoring and adherence to treatment. Yet, many caregivers confront barriers to ensuring children's care, including fear of disclosure of the child's or the parents' HIV status, competing family demands, fluctuating care arrangements and broader structural factors such as entrenched poverty or alternative beliefs about HIV's aetiology and treatment. Thus, many children are "falling through the gaps" because their access to testing and care is mediated by guardians who appear unable or unwilling to facilitate it. These children are likely to suffer treatment failure or death due to their caregivers' recalcitrance. Discussion: This Commentary presents three cases from paediatric HIV services in Zimbabwe that highlight the complexities facing health care providers in providing HIV testing and care to children, and discusses the implications as a child's rights issue requiring both legal and programmatic responses. The cases provide examples of how disagreements between family members about appropriate care, conflicts between a child and caregiver and religious objections to medical treatment interrupt children's engagement with HIV services. In all three cases, no social or legal mechanisms were in place for health staff to intervene and prevent "loss to follow up." Conclusions: We suggest that conceptualizing this as a child's rights issue may be a useful way to raise the debate and move towards improved treatment access. Our cases reflect policy failure to facilitate access to children's HIV testing and treatment, and are likely to be similar across international settings. We propose sharing experiences and encouraging dialogue between health practitioners and global advocates for children's right to health to raise awareness that children are the bearers of rights even if they lack legal capacity, and that the failure of either the state or their caregiver to facilitate access to care is in fact a rights violation.