In vivo measurement of neurotransmitters in cerebrospinal fluidic (CSF) is an effective method to monitor neuronal activities. Microdialysis coupled with HPLC or capillary electrophoresis (CE) is a powerful approach for in vivo monitoring of neurotransmitters. HPLC requires relative large sample volumes (e.g. 5-15 ?L), which is infeasible for limited availability of CSF [1], whereas CE is able to analyze nano- or pico-liter samples in a short time such as 20 seconds. We have developed an integrated CE system targeting on in vivo measurements of essential neurotransmitters. This CE system employs laser-induced fluorescence detectors, and online fluorogenic derivatization. Experimental results show that this system is capable of performing long-term monitoring with robustness, accuracy, high sensitivity and reproducibility in a real-time fashion.