BACKGROUND: Stem cells of adult origin have been used clinically for 40 years in the treatment of haematological neoplasms such as leukaemia. These cells were originally obtained from bone marrow, but are now also being derived from umbilical cord blood. OBJECTIVE: With the increasing public awareness of stem cell use, general practitioners need to be aware for which disorders these cells can, and are, being used. DISCUSSION: Recent clinical trials with stem cells have been for ischaemic heart disease and to assist nonunion of bone. Other adult stem cells used in clinical trials include olfactory cells for spinal cord lesions, and human fetal pancreatic cells for type 1 diabetes. Adult stem cells, however, have limited potential to differentiate into different cell types. Human embryonic stem cells can be converted into cells of all lineages. They first became available for research in 1998 but are yet to be used in clinical trials.