The association of obstructive uropathy with ascites has been known since 1863 and with pleural effusion since 1954. Urinothorax is a rare complication of blunt renal trauma, ureteral instrumentation or ureteral surgery. Leakage from the urinary tract may cause urinoma, retroperitoneal collection of fluid, which can lead to urinothorax. This case report describes a child with a massive right-sided pleural effusion that was caused by same-sided renal calculi. The effusion disappeared within a few days after adequate urinary drainage had been established.