Boldenone (developmental code name RU-18761), is a naturally occurring anabolic–androgenic steroid (AAS) and the 1(2)-dehydrogenated analogue of testosterone.

[3][4] Boldenone occurs naturally in the scent gland of Ilybius fenestratus, a species of aquatic beetle.

[7] One of these was boldenone undecylenate, which was introduced for clinical use under the brand name Parenabol and saw some use in the late 1960s and early 1970s.

[7] Subsequently, boldenone undecylenate was introduced by Squibb under the brand name Equipose for veterinary use, most commonly in horses.

[6] It is marketed as a veterinary combination drug with methandriol under the brand name Drive.