Demand for HIV counselling services is increasing in developing counties, but there have been few previous studies that describe counsellors' roles and experiences providing HIV-related counselling in developing countries. Such information can be used to better supervise and support counsellors and thereby improve counselling services. As a sub-study of the Voluntary Counseling and Testing Efficacy Study, we conducted focus groups and individual interviews with 11 counsellors and counselling supervisors providing HIV counselling services in Kenya and Tanzania. Counsellors told us that their jobs were both rewarding and stressful. In addition to their obligations in the counselling relationship (providing information, protecting confidentiality and being non-judgemental), they perceived pressure to provide information and be good role models in their communities. Additional stresses were related to external (economic and political) conditions, 'spillover' of HIV issues from their personal lives and providing counselling in a research setting. Counsellor stress might be reduced and their effectiveness and retention improved by (1) allowing work flexibility; (2) providing supportive, non-evaluative supervision; (3) offering alternatives to client behaviour change as the indication of counsellor performance; (4) acknowledging and educating about 'emotional labour' in counselling; (5) providing frequent information updates and intensive training; and (6) encouraging counsellor participation in the development of research protocols.