异吲哚（Isoindole）是一种苯并杂环化合物，是吲哚的位置异构体。其环结构存在于酞菁染料和一些生物碱中。

异吲哚存在互变异构，在溶液中，2H-异构体占优势。平衡趋向2-H异构体的程度取决于溶剂种类和分子的取代基。

Isoindole in heterocyclic chemistry is a benzo-fused pyrrole. The compound is an isomer of indole. Its reduced form is isoindoline. The parent isoindole is a rarely encountered in the technical literature, but substituted derivatives are useful commercially and occur naturally. Isoindoles units occur in phthalocyanines, an important family of dyes. Some alkaloids containing isoindole have been isolated and characterized.