The results of the study on the efficacy and safety of the valdoxan (agomelatine) in the treatment of patients with major depressive disorder and insomnia are presented. The study included 64 patients (mean age 45.0±11.7 years). Agomelatine was given in dosage of 25-50 mg for 6 weeks. The following scales were used: HAMD-21, HADS, subjective sleep characteristics scale, sleep apnea screening questionnaire, the Epworth sleepiness scale. All the patients underwent night polysomnography. The use of agomelatine led to the improvement of affective symptoms on HAMD-21 and HADS from the first week of treatment. To the last visit, clinical symptoms of depression disappeared in 29 (49.5%) patients. Simultaneously, subjective sleep quality increased from 12.2±3.2 to 14.7±4.2 points on the appropriate scale and continued to improve. Polysomnography revealed the increase in the total sleep time, the time spent in stage 2, 4 and REM sleep as well as in sleep efficiency index. The sleep latency, number of awakenings and wake time decreased during sleep. The authors conclude that the use of agomelatine in standard dose reduces affective disorders and improves night sleep in patients with depressive disorder and insomnia.