Nilutamide, sold under the brand names Nilandron and Anandron, is a nonsteroidal antiandrogen (NSAA) which is used in the treatment of prostate cancer. It has also been studied as a component of feminizing hormone therapy for transgender women and to treat acne and seborrhea in women. It is taken by mouth.

Side effects in men include breast tenderness and enlargement, feminization, sexual dysfunction, and hot flashes. Nausea, vomiting, visual disturbances, alcohol intolerance, elevated liver enzymes, and lung disease can occur in both sexes. Rarely, nilutamide can cause respiratory failure and liver damage. These unfavorable side effects, along with a number of associated cases of death, have limited the use of nilutamide.

Nilutamide acts as a selective antagonist of the androgen receptor (AR), preventing the effects of androgens like testosterone and dihydrotestosterone (DHT) in the body. Because most prostate cancer cells rely on these hormones for growth and survival, nilutamide can slow the progression of prostate cancer and extend life in men with the disease.

Nilutamide was discovered in 1977 and was first introduced for medical use in 1987. It became available in the United States in 1996. The drug has largely been replaced by newer and improved NSAAs, namely bicalutamide and enzalutamide, due to their better efficacy, tolerability, and safety, and is now rarely used.

It is on the World Health Organization's List of Essential Medicines.