Point-of-care testing (PoCT) is now possible in many areas of clinical medicine. This review examines the evidence for its application in four areas: self-monitoring; community testing primarily in the pharmacy; general practice; and the emergency department. In all of these areas except pharmacy, randomised controlled trials of PoCT versus central laboratory testing have been performed, with the results of some of these trials supporting the use of PoCT. Aside from providing evidence, these trials and other observational studies have provided valuable information about how PoCT should be conducted. In particular they have shown that adoption of the technology is often insufficient to achieve a benefit and in some cases a change of care process is also required.