An open non-randomized controlled prospective study was conducted to investigate the efficacy and safety of valdoxan in the treatment of depression as monotherapy and in the combination with other drugs. Based on the clinical and psychometric measures, author confirmed the high efficacy of valdoxan. The drug can be combined with other antidepressants, no adverse effects are observed in these cases. Positive changes in sleep patterns during the treatment with valdoxan were found. The high tolerability and minimal risk of serious adverse effects were observed. Preliminary data revealed that the age of the patient and scores on some HAMD items were predictors of treatment efficacy. The authors developed a computer program for express-assessment of probability of remission and response to treatment.