Decompressive craniectomy (DC) is a life-saving procedure to control refractory intracranial pressure after traumatic brain injury. Postdecompressive craniectomy hydrocephalus (PDCH) is debilitating complication following DCs. Lumbar drainage (LD) is a temporary measure that is helpful in the assessment of PDCH and its functioning can predict the risks and benefits of definitive cerebrospinal fluid (CSF) diversion procedures. LD is associated with multiple complications. Intracranial hemorrhage is a rare but devastating complication following LD. Here, the authors report a case in which LD was performed as a temporary measure to assess PDCH, resulting in brain stem hemorrhage (BSH). A 45-year-old male underwent DC for severe traumatic brain injury. Patient developed PDCH in postoperative period. LD was done as a bridging procedure for definitive CSF diversion procedure, which resulted in fatal BSH. Authors conclude that although a simple procedure, LD can be associated with fatal BSH. Since drainage of CSF after LD is unpredictable in patients of PDCH, a close monitoring of the functioning of the LD system is required to avoid overdrainage and brain herniations.