In May 2009 the European Aerosol Research Lidar Network (EARLINET) started an intercomparison campaign took place in Leipzig, Germany. The main objective was to compare the mobile Earlinet-LIDARs to have characteristically reference systems and to ensure permanent qualitative Measurements. To test the LIDAR of the Leipziger Institute for Meteorology (LIM) measurements during the comparison time periods were performed and compared to two EARLINET – LIDARs. The main objective was to compare the range-corrected total signal as well as backscatter and extinction coefficients to get information of the accuracy of the system for further independent measurements in the future. It will be shown that the ALS300 is able to achieve results which are in agreement to other lidar systems. However the deviation to the other Lidars depends strongly on the background radiation so that there is a smaller deviation of the mean signal during nighttime measurements then daytime measurements.