Research conducted in South Africa and other parts of the world has revealed that people living with HIV/AIDS (PLWHA) are more at risk of developing a mental disorder than the general population. It makes sense to explore means of integrating HIV/AIDS and mental health care thereby facilitating access of PLWHA to prompt mental health care. We conducted qualitative interviews with 22 HIV/AIDS service providers of three occupational categories (10 nurses, six adherence counsellors and six patient advocates) at three primary health care clinics in the Western Cape, South Africa. We explored the issues of knowledge and practice in mental health care as well as the role of nurses and lay health workers in providing mental health care to PLWHA thereby attempting to integrate mental health and HIV/AIDS care. Although the majority of participants were in favour of mental health screening for PLWHA, they lacked confidence to conduct the screening themselves. Most participants displayed poor knowledge of mental disorders and reported that they referred to colleagues or to an external mental health service if they suspected a possible mental disorder in a patient. Integration of mental health and HIV/AIDS care has potential benefit to the public HIV/AIDS care system. Mental health training should be provided to HIV/AIDS service providers in this regard.