吉西他滨（英语：Gemcitabine），是用于化学疗法的核苷类似物。礼来公司的注册商品名为健择（Gemzar）。

结构是去氧胞苷2'碳上的氢原子换成了氟原子。与5-氟尿嘧啶和其它嘧啶类似物一样，药物在DNA复制时改变了核酸的一个组分，吉西他滨改变的是胞苷。

Gemcitabine (pronunciation: jem-SITE-a-been) is a nucleoside analog used as chemotherapy. It is marketed as Gemzar by Eli Lilly and Company.

It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system.