Giant prostatic urethral stones have been reported as a very rare entity, and the etiology of these stones is not clear. We report a case of a 40-year-old man with giant multiple prostatic urethral stones whereby the entire gland was replaced, and a big ureteral stone presented with voiding difficulty and recurrent urinary tract infections. In the literature, to our knowledge, this is the youngest case wherein giant prostatic urethral stones coexisted with a big ureteral stone. Many different-sized stones were observed endoscopically, some protruding into the urethra, and some filling different cavities on the prostate. Following cystoscopy, multiple giant prostatic stones weighing a total of 151 g were removed by the open retropubic route. We treated the big ureteral stone endoscopically.