zh:zh|α-胎儿蛋白 α-胎儿蛋白（英语：Alpha-Fetoprotein，缩写AFP；又译甲种胎儿球蛋白或甲胎蛋白）是一种α-1球蛋白，由胎儿肠胃道、卵黄囊及肝脏分泌，但可经由肾脏排入尿液、羊水，并通过胎盘进入母体血流中。在正常妊娠时，胎儿血清中之胎儿蛋白浓度于12至14周间达到最高，而母体血清中之浓度则于28至32周间达到最高。如果羊水或母体血清中α-胎儿蛋白超过正常范围，需考虑胎儿发育异常；诸如：神经管缺损，先天性肾病变，肠道闭锁、死胎、胎儿窘迫……等。也就是说，α-胎儿蛋白虽是一项非特异指标，但对于产前评估胎儿健康状态甚具临床价值，也是帮助检查胎儿异常之一项筛检工具。

Alpha-fetoprotein (AFP, α-fetoprotein; also sometimes called alpha-1-fetoprotein, alpha-fetoglobulin, or alpha fetal protein) is a protein that in humans is encoded by the AFP gene. The AFP gene is located on the q arm of chromosome 4 (4q25).

AFP is a major plasma protein produced by the yolk sac and the liver during fetal development. It is thought to be the fetal form of serum albumin. AFP binds to copper, nickel, fatty acids and bilirubin and is found in monomeric, dimeric and trimeric forms.