腕龙科（Brachiosauridae）是蜥脚下目恐龙的一科。牠们是群草食性四足恐龙，前肢长于后肢，并拥有45度角倾斜的长颈部。尽管腕龙科恐龙的外表有独特特征，但牠们的分类仍有争论，腕龙科到底是独立的一科，或是基础巨龙形类恐龙的集合群。因此，关于哪些属该分类于腕龙科也有所争论。

腕龙科恐龙的重量范围从20公吨到90公吨，牠们长而挺立的颈部可让牠们接触到树梢上的树叶，而这范围是其他蜥脚类恐龙所接触不到的。颈椎约在14个左右，内部中空，可减轻牠们的重量。牠们的牙齿长、呈匙状，与其他蜥脚类恐龙相比（例如梁龙），更能处理较坚硬的植物。有些古生物学家推测如果牠们能够以后肢站立，那牠们能够接触到更高层的树枝。然而，牠们的短尾巴与后肢使牠们的重心位在相当前面的部位，将使牠们很难以后肢站立。

Brachiosauridae is a family of sauropod dinosaurs belonging to Titanosauriformes. They were herbivorous quadrupeds with longer forelegs than hind legs, the name derives from the Greek for arm lizard - and long necks. Despite their apparently distinctive features, there is some dispute as to whether Brachiosauridae is really a distinct family or a collection of basal Titanosauriformes. As a result, there is also some dispute about which animals belong within this family.