Intradiscal electrothermal therapy (IDET) is a controversial procedure. Differences in efficacy are affected by differences in selection criteria and technique. Survey data have shown that IDET is not always performed on properly selected patients. Poor practice, therefore, leads to poor outcomes. The best results have been obtained when patients are selected according to strict criteria, including pressure monitored discography and postdiscography CT; and when efforts are made to place electrodes as far possible posteriorly in the annulus. Group data from observational studies mostly attest to modest but definite improvements in pain and function. However, controlled studies have shown outcomes with 50% of patients, or more, deriving no benefit. The remainder, however, derive substantial benefit, with one in five obtaining complete relief of pain. Placebo responses do occur but do not account for all observed, favorable effects. The efficacy of IDET is possibly limited by small size of the lesion produced by the electrodes. More consistent outcomes might be achieved by devices that increase the volume of tissue coagulated.