Objective. This study was performed to analyze the potential for using different methods to increase the efficacy of the psychopharmacotherapy of late depression, particularly by increasing the duration of treatment. Materials and methods. The study included 378 patients aged 50–82 (mean 60.6 ± 8.4) years. Treatment duration effects were studied by dividing patients into groups with short (4–8 weeks), intermediate (12 weeks), and long (20–24 weeks) durations of psychopharmacotherapy. Results and conclusions. Treatment results for durations of less than 8 weeks were significantly worse than those obtained with treatment duration greater than 12 weeks (these groups were not comparable because the initial cohorts were not comparable). By week 24, treatment responses were obtained in 63.9% of patients who had not responded to treatment by week 12, and 43.4% achieved remission. Partial responses and stable positive improvements by 12 weeks (about half the patients achieved remission) were predictors of responses with treatment durations of up to 24 weeks. These data were used to develop algorithms for selection of therapeutic tactics in patients with late depression depending on the results obtained at the first 12 weeks of psychopharmacotherapy.