This study investigated the frequency of poor outcome at discharge of acute subdural hematoma (SDH) patients with and without microbleeds. We retrospectively examined the records of 37 patients with acute SDH who were surgically treated with hematoma removal and received magnetic resonance (MR) imaging within 2 weeks of head injury onset. MR images were used to determine the presence or absence of microbleeds and contusional hemorrhage (CH). Patient outcome was categorized as good (moderate disability or good recovery) or poor (severely disability, vegetative state, or dead) according to the Glasgow Outcome Scale at discharge. Microbleeds were found in 23 patients (62%) and CH was found in 26 patients (70%). Fifteen patients (41%) had both microbleeds and CH. Poor outcome at discharge was more common in SDH patients with both microbleeds and CH than in SDH patients with neither microbleeds nor CH (14/15, 93% vs. 14/22, 64%; p = 0.04). Poor outcome at discharge was more common in SDH patients under 60 years of age with microbleeds (6/8, 75%) than patients under 60 years of age without microbleeds (0/4, 0%; p = 0.03). The location of the microbleed was not related to the outcome at discharge. These results suggest that the presence of microbleeds and CH on MR images may indicate poor prognosis in patients with acute SDH.