八關齋，佛教在家教徒規範的一種，其名目和條文、受持期限，以及天神巡查、鬼神護持等相關內容，早見於《阿含經》及相對應巴利語經篇，可見在佛教成立不久，八關齋之說已趨完備。其後的漢譯佛典，對受持威儀、授受者身分、受持日子和支數等，說法更多；並就不非時食是否八支之一，產生爭議。由於受持八關齋簡便靈活，融入成為漢化佛教以至中土民間信仰的一個重要元素，疑偽佛經亦多提及，凡此令有學者以為八關齋實受中土祭祀傳統或道教影響才成立。八關齋雖耳熟能詳，但未見全面和細緻的探究。本文除對漢譯佛典的相關記述作通盤整理和研究外，並以之為基礎，檢視八關齋是否源於印度，期望對佛教的在家律制及其與中土關係，有更清晰的瞭解。

The Eightfold Observance is a kind of lay Buddhist discipline. Its name and precepts, the period of observance, and related issues such as the inspection and protection of gods are found in the Chinese Āgama Sūtras and the corresponding Pāli discourses, the oldest Indian Buddhist scriptures. In the subsequent Chinese translations of Buddhist texts, varied ideas about the deportment of observance, the identity of the observer, the date of observance and the number of precepts proliferated and the status of the precept “no eating out of regulation hours” gave rise to heated discussions. As the Eightfold Observance is simple and flexible,it becomes an important component of Sinicized Buddhism and folk beliefs in China andis mentioned in many Buddhist apocrypha. Some scholars even speculate that the practice of the Eightfold Observance is actually inspired by Chinese sacrificial rituals or Daoism.Though widespread and well-known, it has yet to receive detailed research. In addition to presenting a comprehensive study of its practice based on the Chinese translations, this article also raises the question of whether the Eightfold Observance originates from Indian Buddhism, with an eye to gain a clearer understanding of this lay Buddhist discipline and its relationship with Chinese culture.