Background: hospitalization of elderly patients is associated with social and psychological maladaptation, reduced levels of daily functioning, and development of hospitalism. Patients whose status suddenly worsened immediately prior to discharge from psychiatric hospital make up a group that is difficult for diagnostics and treatment and not sufficiently studied. The aim of the study was to analyze changes in patients’ status before planned discharge from hospital to identify clinical patterns of deterioration and factors associated with this adverse event. Patients and methods: study participants were selected from 181 consecutive patients of the Geriatric Psychiatry Department of V.M. Bekhterev National Medical Research Center for Psychiatry and Neurology. The main study methods were history-taking and psychological assessment. Results: predischarge deterioration was observed in 81 patients (44.8%) and was represented by exacerbation of mental disorder in 60 cases (33.2%), development of new symptoms in 12 patients (6.6%), or decompensation of somatic disease in 9 cases (5.0%). The history of patients with predischarge worsening was characterized by longer prior hospitalizations. These patients were more heavily pretreated, and had higher rates of hospitalism and non-compliance. For patients with worsening or development of new symptoms of mental disorder median duration of mental disease was respectively 84 and 204 months. They were more prone to violation of compliance, of the prescribed treatment regime and doses. Somatic decompensation occurred in patients with median duration of mental disorder 36 months and was associated with latent refusal to take medicines. Conclusions: an increased risk of predischarge deterioration in geropsychiatric patients with a history of prolonged hospitalizations needs earlier rehabilitation, psychotherapy, and psychological support when planning hospital discharge.