Abstract Powerful and diverse countertransference reactions in psychotherapy group work with HIV positive children can be understood to indicate a site of mourning in the life of the group. Data from six interviews with five individuals conducting broadly psychodynamic group work with HIV positive children was analysed according to Thematic Content Analysis. The countertransference responses of the participants are understood as communications of the group unconscious, as well as expressions of the participants’ own unresolved unconscious difficulties. Working with HIV positive children confronts the participants with mortality and activates their earliest losses. A sense of strangeness and displacement, denial, idealisation, feelings of persecution, fantasies of rescue, rage, despair and hopelessness emerge in the countertransference and can be considered indicative of defences against mourning. These defences alternate with an engagement with the work of mourning and are represented in the countertransference as the relinquishment of omnipotence, awareness of fusion, containment, the recognition of the child’s resilience and uniqueness and the promotion of the child’s autonomy and expression. These findings may facilitate containment for therapists working with HIV positive children by offering an explanation of powerful and diverse countertransference responses as indicating a site of mourning, thereby promoting increased receptivity to unexpressed grief in therapy with these children.