Aerosol Raman lidar observations of profiles of the particle extinction and backscatter coefficients and the respective extinction-to-backscatter ratio (lidar ratio) were performed under highly polluted conditions in the Pearl River Delta (PRD) in southern China in October 2004 and at Beijing during a clear period with moderately polluted to background aerosol conditions in January 2005. The anthropogenic haze in the PRD is characterized by volume light-extinction coefficients of particles ranging from approximately 200 to 800{\text{Mm}}^{-\text{1}} and lidar ratios mostly between 40 and 55 sr (average of 47\pm 6\text{\hspace{0.17em} sr} ). Almost clean air masses were observed throughout the measurements of the Beijing campaign. These air masses originated from arid desert–steppe-like regions (greater Gobi area). Extinction values usually varied between 100 and 300{\text{Mm}}^{-\text{1}} , and the lidar ratios were considerably lower (compared with PRD values) with values mostly from 30 to 45 sr (average of 38\pm 7\text{\hspace{0.17em} sr} ). Gobi dust partly influenced the observations. Unexpectedly low lidar ratios of approximately 25 sr were found for a case of background aerosol with a low optical depth of 0.05. The low lidar ratios are consistent with Mie-scattering calculations applied to ground-based observations of particle size distributions.