This study presents two adult patients who experienced pleural effusion during hospitalization for stroke rehabilitation therapy after ventriculoperitoneal shunt placement for normal pressure hydrocephalus associated with aneurysmal subarachnoid haemorrhage. The pleural effusion appeared without migration of the catheter into the thoracic cavity. Because of respiratory insufficiency, which prevented progress in their rehabilitation programme, thoracentesis was repeated for recurrent pleural effusions, the composition of which differed significantly from that of cerebrospinal fluid. Both cases had past histories of laparostomies; therefore, the distal end of the catheter was placed in the right anterior subphrenic recess. One was able to resolve the pleural effusion and rehabilitate the patients by replacing the ventriculoperitoneal shunt with a vetriculoatrial shunt. In the literature, there have been only 23 reports of pleural effusion associated with a ventriculoperitoneal shunt. Among those reports, four involved pleural effusion without migration of the distal catheter; however, all of those cases were in children. Thus, this study reports the first adult cases of pleural effusion without migration of the catheter into the pleural cavity and discusses a putative mechanism.