We report optical frequency comb drift stabilization of an external cavity semiconductor laser hybridly modelocked at the 10 GHz cavity fundamental using the Pound-Drever-Hall frequency stabilization scheme. Laser longitudinal mode comb was locked to a Fabry-Perot reference cavity with a finesse value of 214. The frequency error signal was fed back to the bias current of the semiconductor gain medium to change the effective laser cavity length through the coupling between carrier density and refractive index. The peak-to-peak 2.4 GHz frequency drift of the comb of longitudinal modes was reduced to a RMS fluctuation of 30 MHz for up to 5 minutes. To the authors" knowledge, this is the first optical frequency comb stabilization of a modelocked semiconductor laser. The intended application of the optical frequency stabilization is to keep the laser optical frequency comb locked to a WDM filter that is used for spatially separating the individual longitudinal modes of the laser for photonic arbitrary waveform generation.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.