Lemon balm (Melissa officinalis L.), member of Lamiaceae family, is one of the important medicinal plant species. In this study we were investigated the effects of Salicylic hydroxamic acid(SHAM) on seed germination and yield of lemon balm. It was conducted at Agriculture Research Center of Hamedan Province in 2013. SHAM used in 4 different concentrations (0, 50, 75, 100 ppm). Seeds were primed for 8 hours in each concentration, and planted in petri dish. Then, we were assessment some parameter such as seed germination, germination speed, root length, root weight, shoot length, shoot weight, seedling dry weight, enzyme activity, catalase, and peroxidase. This study indicated that SHAM had significant effects on all germination traits and biochemical parameters. Comparison of mean effects of SHAM revealed that the highest germination percent (89%), germination speed (5.41), shoot length (21.15 mm), root length (17 mm), fresh weight (38 mg) and dry weight (8.12 mg). The highest catalase enzymes (23 micromole/mg) and highest peroxidase action (25.66 micromole/mg) were observed at the control concentration. It can be concluded that the SHAM has antioxidant properties and regulate resporiratory system.