After the middle of May 1981 lidar observations at Garnisch-Partenkirchen recorded a marked enhancement of the aerosol backscattering from the lower stratosphere. Until the end of July several distinct aerosol layers could be detected which thereafter merged into a broad homogeneous layer. The eruption of volcano Alaid, Kurile Island, on 28 April is supported as the source of this recent stratospheric aerosol increase. This aerosol disturbance is of about the same magnitude as that caused by Mount St. Helens in May 1980. Significant climatic effects are not predicted.