Blood causes striking changes on computerized tomography. However, chronic subdural hematomas may become isodense with brain and therefore not visible directly. Midline and ventricular displacement, effacement of cortical sulci, narrowing of white matter on one side, and ventricular distortion should suggest a unilateral isodense process. Bilateral isodense subdural hematomas pose a major problem on computerized tomography since there are no indications of a mass lesion. A negative report could lull the clinician into a false sense of security. In these cases, general disappearance of sulci and considerable narrowing of ventricles are helpful findings. A particularly important and overlooked sign is an abnormally decreased bicaudate cerebroventricular index. Above all, a high degree of suspicion is vital.