We describe a complete diode laser system stabilized at 852 nm on theD2line of Cs with a linewidth narrower than 100 kHz. This system is intended to be employed for optical pumping, cooling, and detection of Cs atoms in atomic frequency standards. The square root of the Allan variance, evaluated by measuring the beat‐note of two similar systems, is better than 1×10−12for &tgr; up to 1000 s. A month of continuous locked operation has been observed.