Postoperative pseudomeningocele is an uncommon complication of craniospinal surgery. Diagnosis is reached on a postoperative computed tomography and magnetic resonance (MR) imaging. Demonstration of the location and dimension of the dural defect before surgical therapy is a very important. T1- and T2-weighted MR images revealed a significant pseudomeningocele extending from left cervicooccipital region. Magnitude and phase-contrast-MR images showed a cerebrospinal fluid (CSF) flow into pseudomeningocele, but they no revealed dural defect. Three-dimensional isotropic T2-weighted SPACE sequence revealed a signal void indicating CSF flow into pseudomeningocele and location and exact size of dural tear. Three-dimensional isotropic T2-weighted SPACE sequence is certainly the noninvasive and optimal method for demonstrating postoperative pseudomeningocele sacs. It demonstrates a pseudomeningocele regardless of an existing communication with the dural membrane.