In this study, we demonstrated FSCV with a carbon fiber microelectrode (CFM) adjacent to a microdialysis probe to measure concentration changes during microdialysis. Experiments were performed in agarose gel (0.1%) with a known concentration of dopamine inside, and perfusion of the dialysis probe with Tris-buffered saline (TBS, pH7.4, 5ul/min) decreased the baseline. After stabilization, a series of known concentrations of dopamine (200nM to 1uM) was perfused and concentration changes were monitored by FSCV until the decreased baseline was recovered. These results indicate that the amount of dopamine injected when decrease baseline is fully recovered reflects the concentration of dopamine inside the agarose gel. FSCV combined with microdialysis was also performed in the striatum of a rat, to monitor basal level of dopamine in the extracellular space of the brain.