Traditional and complementary systems of medicine (TCM) encompass a broad range of practices which are commonly embedded within contextual cultural milieu, reflecting community beliefs, experiences, religion and spirituality. Evidence from across the world, especially from low- and middle-income countries (LMIC), suggests that TCM is commonly used by a large number of persons with mental illness. Even though some overlap exists between the diagnostic approaches of TCM and conventional biomedicine (CB), there are major differences, largely reflecting differences in the understanding of the nature and etiology of mental disorders. However, treatment modalities employed by providers of TCM may sometimes fail to meet common understandings of human rights and humane care. Still, there are possibilities for collaboration between TCM and CB in the care of persons with mental illness. Research is required to clearly delineate the boundaries of such collaboration and to test its effectiveness in bringing about improved patient outcomes.