Ethylestrenol, also known as ethyloestrenol or ethylnandrol and sold under the brand names Maxibolin and Orabolin among others, is an androgen and anabolic steroid (AAS) medication which has been used in the past for a variety of indications such as to promote weight gain and to treat anemia and osteoporosis but has been discontinued for use in humans.

[2] Ethylestrenol has very low affinity for human serum sex hormone-binding globulin (SHBG), less than 5% of that of testosterone and less than 1% of that of DHT.

[2] This is in accordance with its very low affinity for the androgen receptor, only about 5% of that of testosterone and 2% of that of dihydrotestosterone.

[5][12][2] Other related AAS include bolenol (3-deketo-17α-ethyl-19-nor-5-androstenediol), ethyldienolone (17α-ethyl-δ9-19-NT), norboletone (17α-ethyl-18-methyl-19-NT), propetandrol (17α-ethyl-19-NT 3β-propionate), and tetrahydrogestrinone (THG; 17α-ethyl-18-methyl-δ9,11-19-NT).

The progestins allylestrenol (3-deketo-17α-allyl-19-NT) and lynestrenol (3-deketo-17α-ethynyl-19-NT) are also closely related to ethylestrenol, differing only by the C17α substitution.

[5][12][13][3] The BANTooltip British Approved Name was formerly ethyloestrenol, but it was eventually changed.

[2] Ethylestrenol is or has also been marketed for veterinary use under the brand names Nandoral, Nitrotain, and Oestrotain.