结缔组织（英语：Connective Tissue）为脊椎动物基本组织之一，由细胞和大量细胞外基质组成。广义上的结缔组织包括固有结缔组织、软骨组织和骨组织、血液以及淋巴。一般所致的结缔组织指固有结缔组织。其中，固有结缔组织又分为疏松结缔组织（蜂窝组织）、致密结缔组织、脂肪组织，以及网状组织。

结缔组织在生物体内起连接、支持、营养、运输和保护等作用。在胚胎发育中，结缔组织系由中胚层的间充质发育而来。

Connective tissue (CT) is one of the four types of biological tissue that support, connect, or separate different types of tissues and organs in the body. It develops from the mesoderm. The other three types are epithelial, muscle, and nervous tissue. Connective tissue is found in between other tissues everywhere in the body, including the nervous system. In the central nervous system, the three outer membranes (the meninges) that envelop the brain and spinal cord are composed of connective tissue.