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A single dose of ulipristal acetate (UPA) 30 mg has recently been approved for emergency contraception (EC) up to 120 h after unprotected intercourse. A meta-analysis of clinical trials comparing UPA with levonorgestrel (LNG) for EC demonstrated that UPA has higher efficacy. Both treatments have similar side effects. The mechanism of action of both LNG and UPA for EC is by delaying or inhibiting ovulation. However, UPA appears to have a direct inhibitory effect on follicular rupture that allows it to be effective even when administered shortly before ovulation, a time period when LNG is no longer effective. This article summarizes clinical data available on UPA for EC and provides evidence that UPA, a second-generation progesterone-receptor modulator, represents a new effective alternative for EC.