Background: To determine whether the use of oral antithrombotic agents before the onset of intracerebral hemorrhage (ICH) affects hematoma features and early patient outcome. Methods: A retrospective, multicenter study involving 1,006 consecutive Japanese patients (607 men, 67 ± 12 years of age) hospitalized within 24 h after the onset of nontraumatic ICH was conducted. Results: One hundred and eighty patients were taking oral antiplatelet agents (17.9%, AP group), 67 were taking warfarin (6.7%, W group), and 21 were taking both (2.1%, W + AP group). After adjustment for age, sex, and known confounders, the taking of each kind of antithrombotic therapy was independently related to cerebellar hemorrhage; the odds ratios (OR) and 95% CI, with patients taking no antithrombotic agents as the reference group, were 2.31 (1.23–4.32) for the AP group, 2.90 (1.26–6.63) for the W group, and 3.43 (1.02–11.59) for the W + AP group. Similarly, the taking of each kind of antithrombotic therapy was independently related to hematoma enlargement within the initial 24 h (OR and 95% CI: AP group, 1.92, 1.10–3.34; W group, 4.80, 2.12–10.87; W + AP group, 4.94, 1.31–18.61) and mortality at 3 weeks post-ICH (OR and 95% CI: AP group, 2.70, 1.56–4.68; W group, 2.50, 1.05–5.96; W + AP group, 9.41, 2.78–31.88). Conclusions: Prior medication with antiplatelet agents, warfarin, or both was predictive of cerebellar hemorrhage, hematoma enlargement, and early death in Japanese ICH patients.