Aerosol optical depth measurements over Issyk-Kul Lake acquired with the handheld sun photometer Microtops II are analyzed. Aerosol found over the mountainous region at the elevation of 1650 m above sea level resembles mostly clean background conditions. The yearly aerosol optical depth at a wavelength 500 nm ~0.10 ¿ 0.03 is in agreement with the multi-year means from the background sites of the Aerosol Robotic Network (AERONET). Over a period of 4 years optical depth showed a seasonal pattern, with a maximum observed during summer. A link has been made between new and previously acquired data in order to provide a reliable trend for the region.