To study the effect of different levels of drought stress on growth, yield and some physiological and phytochemical characteristics of oregano (Origanum vulgare L. ssp. gracile), a pot experiment, in a randomized complete design with four treatments and five replications, was conducted. Drought stress treatments were 100% (non-stress), 80%, 60% and 40% of field capacity. The results showed that drought stress had significant effect on growth parameters, dry herb yield, leaf relative water content (RWC), total phenol and flavonoid content, antioxidant activity, a, b and total chlorophyll content, essential oil content and yield. There was no significant difference between drought stress treatments for carotenoids. As the soil water content decreased, plant height, stem diameter, number and length of axillary shoots, dry herb yield, RWC, a, b and total chlorophyll content and essential oil yield decreased, but total phenol and flavonoid content, antioxidant activity and essential oil content increased. Despite the decrease in dry herb yield, the difference between 80%, 60% and 40% treatments was not significant. The highest essential oil content (1. 54 ml/100 g DW) was observed in 60% of field capacity and the highest amounts of total phenol (5. 21 mg gallic acid/g FW), total flavonoid (0. 5 mg quercetin/g FW) and antioxidant activity (77. 36%) were obtained in 40% of field capacity. The highest percentage of essential oil (54. 1 mg / g dry matter) was observed in 60% of treatment capacity and the highest amount of total phenol (0. 51 mg gallic acid per gram of fresh material), total flavonoid (0. 5 mg Gram quercetin in grams of fresh milk) and antioxidant activity (37. 36%) in 40% of treatment capacity.