Salvia sclarea (Clary sage, Lamiaceae) is commonly known as 'misk ada cayi' in Turkey. It is widely cultivated for extractive purposes in France, Bulgaria and USA. This study was designed to examine the effect of seasonal variation oil in vitro antimicrobial and antioxidant activities of methanolic extract of Clary sage. The results indicated that the extract of the plants collected in midday contained higher levels of phenolic content and revealed higher antioxidant capacities compared to the materials collected at other times of the day. No differences were found between the methanolic extract of the plants collected at the years of 2005 and 2006 for phenolic content and antioxidant activities. Antimicrobial activities of the extracts against thirteen microorganisms were also investigated. Salmonella typhimurium was the most resistant microorganism whereas Aeromonas hydrophila, Bacillus brevis and Bacillus cereus were the most sensitive microorganisms to the all extracts examined in this study.