耗散系统（Dissipative system）是指一个远离热力学平衡状态的开放系统，此系统和外环境交换能量、物质和熵而继续维持平衡，对这种结构的研究，解释了自然界许多以前无法解释的现象。

耗散结构一词由比利时物理学家、化学家伊里亚·普里高津发明。普里高津创立了耗散结构理论，研究一个系统从混沌无序向有序转化的机理、条件和规律的科学，他为此曾获1977年诺贝尔化学奖。

常见的耗散结构包括对流、气旋、热带气旋及生物体。像镭射、瑞利–贝纳尔对流及B-Z反应也是耗散结构的例子。

A dissipative system is a thermodynamically open system which is operating out of, and often far from, thermodynamic equilibrium in an environment with which it exchanges energy and matter.

A dissipative structure is a dissipative system that has a dynamical régime that is in some sense in a reproducible steady state. This reproducible steady state may be reached by natural evolution of the system, by artifice, or by a combination of these two.