Purple urine bag syndrome (PUBS) is a medical syndrome where purple discoloration of urine occurs in people with urinary catheters and co-existent urinary tract infection. Bacteria in the urine produce the enzyme indoxyl phosphatase. Discolouration of the urine bag is due to the presence of indigo and indirubin pigments which precipitate and react with the synthetic materials of the catheter and urinary bag. We present a case report of this rare phenomenon.