Bathtub gin refers to any style of homemade spirit made in amateur conditions. The term first appeared in 1920, in the prohibition-era United States, in reference to the poor-quality alcohol that was being made.

As gin was the predominant drink in the 1920s, many variations were created by mixing cheap grain alcohol with water and flavorings and other agents, such as juniper berry juice and glycerin. Contrary to popular belief, the spirit was not made in a bathtub. Rather, because the preferred sort of bottle was too tall to be topped off with water from a sink, they were filled from a bathtub tap, as well as sometimes distilled from and fermented in a bathtub.

Many cocktails owe their existence to bathtub gin, as they were also created in order to mask the awful taste.

Bathtub Gin is also a gin brand produced by Master of Malt in the UK. Whilst not being made in a bathtub it produced using compounding/infusing rather than using botanical distillation.