The design and fabrication of a microfluidic cytometer system and its application for reticulocyte detection are described. This chip can count the target cells, which are focused at the detection window without sheath flow. This cytometer system based on optimized epifluoresence has a competitive advantage in the signal-to-noise ratio. Induced fluorescence from the reticulocyte binded with antibody is detected by the optical module and then transformed into the electronic signal by a photo multiplier tube. After signal processing, the results are automatically read out by a digital module and displayed on the system. To evaluate this microfluidic cytometer system, experiments employing polystyrene (