In vivo voltammetry is approaching the end of its second decade as a technique to explore extracellular concentrations in the brain. The issues of selectivity and sensitivity, which caused considerable discussion and confusion in the early 1980s, are now resolved. It is clear that in vivo voltammetry and dialysis are complimentary tools to understand neurotransmitter dynamics. The two chief advantages of voltammetry compared to dialysis, improved temporal resolution and reduced tissue damage, make this technique exceptionally well suited for providing information which is complementary to that obtained by single-unit recording and is uniquely capable of providing information on the short-term regulation of extracellular levels of biogenic amines.