Depression is a common disease affecting more than 300 million people worldwide. Since Lippia sidoides has shown central nervous system effects in previous works, we aimed to investigate the effect of L. sidoides essential oil and its major compound, thymol on a corticosterone-induced depression model in mice. Male mice (20–25 g) received corticosterone (20 mg/kg, subcutaneously), once a day for 22 days. From the 16th day on, mice were grouped to receive either corticosterone or L. sidoides essential oil (100 and 200 mg/kg), or thymol (25 and 50 mg/kg) or fluoxetine (35 mg/kg) by gavage. The forced swimming test, tail suspension, open field, elevated plus maze and sucrose preference tests were performed from the 19th to 22nd day. Data were analyzed by ANOVA followed by the Student-Newman-Keuls as a post hoc test and the results were considered significant when p