The molecular formula C₂₁H₂₈O₂ may refer to:

• 11-Dehydroprogesterone
• Demegestone
• Dextronorgestrel
• Dydrogesterone
• Ethisterone, a progesterone hormone
• Guggulsterone
• Levonorgestrel
• Norboletone
• Norgestrel, a progestin
• Tetrahydrogestrinone, an anabolic steroid
• Tibolone, a steroid hormone
• Δ4-Tibolone, a metabolite of tibolone

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