Objective: to analyze clinical and pathoanatomic characteristics of hemostatic disorders in patients with severe leptospirosis; to assess the type, frequency, and dynamics of hemorrhagic and thrombotic symptoms in patients with leptospirosis; to identify predictors of lethal outcome. Patients and methods. The study included 505 patients with serologically confirmed severe leptospirosis aged between 15 and 76 years. Of them, 474 patients recovered, whereas 31 patients died. We performed comparative analysis of independent categorical (binary) variables using contingency tables and Pearson's χ test with Yates' correction. We calculated odds ratios (ORs) and confidence intervals (CIs). Results. More than half of patients with severe leptospirosis (56%) had hemorrhagic syndrome; more than two-thirds of patients (72.6%) had symptoms of thrombosis. We identified the following risk factors for lethal outcome: presence of ≥ 3 hemorrhagic symptoms (ОR = 19.2 [8.5–43.2]), petechial rash in multiple areas (ОR = 11.4 [5.1–26.6]), gastrointestinal bleeding (ОR = 8.6 [3.7–20.1]), gross hematuria (ОR = 5.2 [1.9–14.0]), and postinjection hematomas (ОR = 4.2 [2.0–9.1]). Pulmonary hemorrhage was always associated with a lethal outcome. Hemostatic disorders were the most common cause of death among patients with leptospirosis. During the first week of the disease, thrombosis and hemorrhagic syndrome primarily affect the lungs (70%), kidneys (65.2%), and adrenal glands (17.4%). During the acute phase of the disease, hemorrhagic syndrome was most severe and hemorrhagic changes were detected in all organs. Later (weeks 3–4), patients usually present with signs of cerebral lesions (hemorrhages of varying severity (52%), myocardial infarctions (8.7%), and gastrointestinal bleeding (22%). 2