During the last 8-10 years the research on homocysteine has become very active. Hundreds of articles are now published each year. A disturbed homocysteine metabolism can be an underlying factor for pregnancy complications and fetal malformations, cardiovascular disease, dementia, psychiatric and neurologic disorders and possibly carcinogenesis. A disturbed homocysteine metabolism can in most cases be normalized by treatment with folate and/or vitamines B 12 and B 6. Many of these findings therefore directly concern most practitioners. However, if there are good reviews covering single aspects of this research, these are published in specialized journals. The author has realized the difficulties for the practitioner in keeping updated.