Summary Background Euthanasia and assisted suicide, and policies to address them are the subjects of contentious debate in many countries. However, the question of why people desire euthanasia or assisted suicide has not been coherently answered. We aimed to answer this question in a specific group of patients. Methods We did a qualitative study of 32 people with HIV-1 or AIDS, who were enrolled in the HIV-1 Ontario Observational Database at Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada. We elicited participants' experiences of deliberation about euthanasia or assisted suicide, and the meaning of these experiences with in-depth, face-to-face interviews. We analysed our data with grounded theory methods. Findings Participants' desire for euthanasia and assisted suicide were affected by two main factors: disintegration, which resulted from symptoms and loss of function; and loss of community, which we defined as progressive diminishment of opportunities to initiate and maintain close personal relationships. These factors resulted in perceived loss of self. Euthanasia and assisted suicide were seen by participants as means of limiting loss of self. Interpretation These determinants of desire for euthanasia or assisted suicide in people with HIV-1 or AIDS have implications for the debate on these practices, and development of policies to regulate them.