Medicinal plants are the main sources of natural antioxidants. Lemon balm (Melissa officinalis L.) belongs to the Lamiaceae family that their leaves have been used as herbal tea for claiming the nervous system. In order to study the impact of drying methods on drying time and qualitative characteristics of lemon balm, an experiment was conducted based on completely randomized design with six replications at the Special Laboratory, College of Agriculture, Ferdowsi University of Mashhad during 2012. Leaves dried at three temperature with oven (30, 40 and 60ᵒC) and natural methods (shaded and sunny airs). The drying process was continued until the moisture content of leaves reduced about 10% based on dry weight. The effects of different drying methods were significant (p≤0.01) on essential oil and Citronellal contents of lemon balm. By increasing in oven temperature was declined drying time for leaves. The maximum Citronellal and essential oil were observed in shaded air (with 0.3 and 53.4%, respectively) and their minimum were in 60ᵒC oven (with 0.02 and 12.5%, respectively).

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