次級獲益之概念最早係由Freud所提出，是一種内在心理機制，可以是潛意識的或是有意識的意圖，最初的定義是患者藉由疾病的結果，所獲得的人際關係或是社會的優勢。由於定義的不明確，導致不同研究者不同的解釋與研究結果，迄今已演變為一複雜且持續擴展的概念，可包含内部的次級獲益和外部的次級獲益。鑑於國内次級獲益相關研究付之闕如，藉由對次級獲益的概念及相關研究之探討，以提供臨床工作者對此概念有更清楚的認識與理解，有助於未來運用於臨床實務中。

Freud first proposed the concept of secondary gain. It is an intra-psychological mechanism and can be unconscious or conscious. The initial definition of secondary gain is as an interpersonal or social advantage attained by the patient since a consequence of the illness. Due to the ambiguity of the definitions, different interpretations and research results of different researchers have evolved into a complex and continuously expanding concept that can include internal secondary gains and external secondary gains. Since there are just too few researches of secondary gain in our country, we should study relevant literature across the world first. The literature study and discussion might help us better understand about this concept and assist clinical workers to apply it to clinical practice in the future.