Urolagnia (also known as urophilia or undinism) is a sexual fetish in which participants derive sexual pleasure from urine and urination. Urolagnia is sometimes associated with, or confused with, Omorashi.

People with urolagnia often like to urinate in public, or urinate on, or be urinated on by other people, and may drink the urine. The consumption of urine is urophagia. Some like to watch others doing these things. These activities are often described by the euphemisms "golden showers" or "watersports".

Some people drink large quantities of their own urine as alternative medicine. This is not the same as urolagnia.